| **Regulatory Matters (Details) (USD $)**                                                                                                     | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | 1 Months Ended                                                                                                                                                                                                                                                                                                | 12 Months Ended                                                                                                                                      | 24 Months Ended                                                                    | 1 Months Ended                                                                                                                                    | 2 Months Ended                                                                                                                                                                                                                             |                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                      |
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| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Description of Regulatory Scope                                                                                            | Our utility operations are regulated by the NCUC, PSCSC and TRA as to rates, service area, adequacy of service, safety standards, extensions and abandonment of facilities, accounting and depreciation. We are also regulated by the NCUC as to the issuance of long-term debt and equity securities. The NCUC and the PSCSC regulate our gas purchasing practices under a standard of prudence and audit our gas cost accounting practices. The TRA regulates our gas purchasing practices under a gas supply incentive program which compares our actual costs to market pricing benchmarks. As part of this jurisdictional oversight, all three regulatory commissions address our gas supply hedging activities. Additionally, all three regulatory commissions allow for recovery of uncollectible gas costs through the PGA. The portion of uncollectibles related to gas costs is recovered through the deferred account and only the non-gas costs, or margin, portion of uncollectibles is included in base rates and uncollectibles expense. |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            | $ 213,867,000us-gaap_RegulatoryAssets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | $ 246,306,000us-gaap_RegulatoryAssets                                                                                                                                                                                                                                                                         |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 29,088,000us-gaap_RegulatoryAssetsCurrent                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 77,204,000us-gaap_RegulatoryAssetsCurrent                                                                                                                                                                                                                                                                     |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Payments to Acquire Property, Plant, and Equipment                                                                                           | 460,444,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | 599,999,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment                                                                                                                                                                                                                                                 | 529,576,000us-gaap_PaymentsToAcquirePropertyPlantAndEquipment                                                                                        |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Operations and maintenance                                                                                                                   | 270,877,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 253,120,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations                                                                                                                                                                                                                                          | 242,599,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Total Amount Of Margin Generated From Secondary Market Activity                                                                              | 97,600,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 35,900,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity                                                                                                                                                                                                                                         | 38,700,000pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity                                                                                |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amount Of Net Secondary Market Margins Flowed Through To Jurisdictional Customers                                                            | 72,200,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 26,900,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers                                                                                                                                                                                                                         | 29,000,000pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers                                                                |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amount Of Net Secondary Market Margins Retained                                                                                              | 25,400,000pny_AmountOfNetSecondaryMarketMarginsRetained                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 9,000,000pny_AmountOfNetSecondaryMarketMarginsRetained                                                                                                                                                                                                                                                        | 9,700,000pny_AmountOfNetSecondaryMarketMarginsRetained                                                                                               |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| North Carolina                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| North Carolina Bond Issuance Amount                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 | 200,000,000pny_StateBondIssuanceAmount/ us-gaap_StatementGeographicalAxis= stpr_NC |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Capital Investments In Integrity and Safety Projects                                                                                         | 241,900,000pny_CapitalInvestmentsInIntegrityandSafetyProjects/ us-gaap_StatementGeographicalAxis= stpr_NC                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Capital Investments In Integrity and Safety Projects                                                                                         | 54,000,000pny_CapitalInvestmentsInIntegrityandSafetyProjects/ us-gaap_StatementGeographicalAxis= stpr_TN                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Deferred operations and maintenance expenses                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 916,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 739,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                                                                                       |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Deferred pipeline integrity expenses                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 3,470,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | 3,149,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                                                                                                                                            |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Environmental costs                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            | 8,000,000us-gaap_RegulatoryAssets/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 1,568,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | 1,480,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                                                                                                                            |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Robeson LNG Development Cost [Member]                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 917,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 382,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                                                                                                                                                                      |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Other Regulatory Assets (Liabilities) [Member]                                                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 1,850,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 1,091,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                                                                                                                                                                         |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member]                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Debt Equity Securities Limit, Amount                                                                              | 1,000,000,000pny_PublicUtilitiesApprovedDebtEquitySecuritiesLimitAmount/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               | 1,000,000,000pny_PublicUtilitiesApprovedDebtEquitySecuritiesLimitAmount/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Request Transfer Plant Held For Future Use To Deferred Regulatory Asset                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          | 6,700,000pny_RequestTransferPlantHeldForFutureUseToDeferredRegulatoryAsset/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Flowed Through To Customers                                                                       | 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Retained                                                                                          | 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | Minimum [Member]                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Target Percentage Range Normalized Sales                                                                                                     | 22.50%pny_TargetPercentageNormalizedSales/ us-gaap_RangeAxis= us-gaap_MinimumMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | Maximum [Member]                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Target Percentage Range Normalized Sales                                                                                                     | 45.00%pny_TargetPercentageNormalizedSales/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | EasternNC Exclusive Franchise Rights [Member]                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| North Carolina Bond Issuance Amount                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              | 149,600,000pny_StateBondIssuanceAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember | 38,700,000pny_StateBondIssuanceAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember | 188,300,000pny_StateBondIssuanceAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_EasternNorthCarolinaNaturalGasCompanyExclusiveFranchiseRightsMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Operational Feasibility Assessment Time Period                                                                                               | 2 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member]                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Overall Rate Base With Approved Rates And Charges                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   | 1,800,000,000pny_OverallRateBaseWithApprovedRatesAndCharges/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember |   |   |   |   |   |
| Public Utilities, Approved Return on Equity, Percentage                                                                                      | 10.00%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Return on Investment, Percentage                                                                                  | 7.51%pny_PublicUtilitiesApprovedReturnonInvestmentPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Equity Capital Structure, Percentage                                                                              | 50.70%us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Approved Annual Average Revenue Percentage Increase From Last Rate Case                                                                      | 0.70%pny_ApprovedAnnualAverageRevenuePercentageIncreaseFromLastRateCase/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member]                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 30,700,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Percentage                                                                              | 3.58%us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member] | Gas Utility Margin [Member]                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 16,800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ pny_ComponentsOfRevenueIncreaseAxis= pny_GasUtilityMarginMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Sales [Member] | Fixed Gas Costs [Member]                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 13,800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ pny_ComponentsOfRevenueIncreaseAxis= pny_FixedGasCostsMember/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Revised Pre-Tax Income [Member]                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 24,200,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= pny_RevisedPreTaxIncomeMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | General Rate Case Proceeding 2013 [Member] | Operating Expense [Member]                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | (10,900,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= us-gaap_OperatingExpenseMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina Public Staff Audit 2011 Gas Cost Review Period [Member]                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Allowed Recovery For Gas Costs                                                                                                 | 100.00%pny_PercentageOfAllowedRecoveryForGasCosts/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NorthCarolinaPublicStaffAudit2011GasCostReviewPeriodMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina Public Staff Audit 2012 Gas Cost Review Period [Member]                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Allowed Recovery For Gas Costs                                                                                                 | 100.00%pny_PercentageOfAllowedRecoveryForGasCosts/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NorthCarolinaPublicStaffAudit2012GasCostReviewPeriodMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina Public Staff Audit 2013 Gas Cost Review Period [Member]                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Allowed Recovery For Gas Costs                                                                                                 | 100.00%pny_PercentageOfAllowedRecoveryForGasCosts/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NorthCarolinaPublicStaffAudit2013GasCostReviewPeriodMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina Public Staff Audit 2013 Gas Cost Review Period [Member] | Subsequent Event [Member]                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       | In November 2014, the NCUC approved our accounting of gas costs for the twelve months ended May 31, 2014. We were deemed prudent on our gas purchasing policies and practices during this review period and allowed 100% recovery.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina Public Staff Audit 2014 Gas Cost Review Period [Member] | Subsequent Event [Member]                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Allowed Recovery For Gas Costs                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       | 100.00%pny_PercentageOfAllowedRecoveryForGasCosts/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NorthCarolinaPublicStaffAudit2014GasCostReviewPeriodMember/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_SubsequentEventTypeAxis= us-gaap_SubsequentEventMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | North Carolina IMR Adjustment 2014 [Member]                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 800,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NorthCarolinaApprovalIMRAdjustmentFebruary2014Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | NCUC Petition for IMR Rate Adjustment Filed December 2014 [Member] | Subsequent Event [Member]                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 26,600,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NCUCPetitionFiledIMRDecember2014Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_SubsequentEventTypeAxis= us-gaap_SubsequentEventMember                                                                        |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | In December 2014, we filed a petition with the NCUC seeking authority to adjust rates to collect an additional $26.6 million in annual IMR margin revenues effective February 1, 2015 based on $241.9 million of capital investments in integrity and safety projects over the twelve-month period ending October 31, 2014. We are waiting on a ruling from the NCUC at this time. |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | NCUC Petition for Limited Waiver 2014 [Member]                                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Operations and maintenance                                                                                                                   | 65,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_NCUCPetitionforLimitedWaiver2014Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | Deferred operations and maintenance expenses                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Deferral Time Period Of Operation And Maintenance Expense                                                                                    | 8 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            | 5,600,000us-gaap_RegulatoryAssets/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 6,400,000us-gaap_RegulatoryAssets/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                  |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | Deferred operations and maintenance expenses | General Rate Case Proceeding 2008 [Member]                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Interest Accrued On Deferred Expenses                                                                                                        | 7.84%pny_InterestAccruedOnDeferredExpenses/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_Generalratecaseproceeding2008Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 12 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   | 9,000,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_Generalratecaseproceeding2008Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember |   |   |   |   |
| NCUC [Member] | Deferred operations and maintenance expenses | General Rate Case Proceeding 2013 [Member]                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Interest Accrued On Deferred Expenses                                                                                                        | 6.55%pny_InterestAccruedOnDeferredExpenses/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 82 months                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Oct. 31,  2020                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   | 6,300,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember |   |   |   |
| NCUC [Member] | Deferred pipeline integrity expenses                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            | 28,200,000us-gaap_RegulatoryAssets/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 19,400,000us-gaap_RegulatoryAssets/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                                                                        |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| NCUC [Member] | Deferred pipeline integrity expenses | General Rate Case Proceeding 2013 [Member]                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 5 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Dec. 31,  2018                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   | 17,300,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember |   |   |
| NCUC [Member] | Environmental costs | General Rate Case Proceeding 2013 [Member]                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 5 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Dec. 31,  2018                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   | 6,300,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember |   |   |   |
| NCUC [Member] | Robeson LNG Development Cost [Member] | General Rate Case Proceeding 2013 [Member]                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   | 1,200,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateCaseProceeding2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember |   |   |   |
| NCUC [Member] | Robeson LNG Development Cost [Member] | General Rate Application Settlement 2013 [Member]                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 38 months                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Feb. 28,  2017                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   | 1,200,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2013Member/ us-gaap_RegulatoryAgencyAxis= pny_NorthCarolinaUtilitiesCommissionMember/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember |   |   |   |
| PSCSC [Member]                                                                                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Flowed Through To Customers                                                                       | 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Retained                                                                                          | 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Maximum Utility Rate of Return Change Allowed Under RSA                                                                                      | 50pny_MaximumUtilityRateofReturnChangeAllowedUnderRSA/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Minimum [Member]                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Target Percentage Range Normalized Sales                                                                                                     | 22.50%pny_TargetPercentageNormalizedSales/ us-gaap_RangeAxis= us-gaap_MinimumMember/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Maximum [Member]                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Target Percentage Range Normalized Sales                                                                                                     | 45.00%pny_TargetPercentageNormalizedSales/ us-gaap_RangeAxis= us-gaap_MaximumMember/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2012 [Member]                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Return on Equity, Percentage                                                                                      | 11.30%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeOfRegulatoryStaffOctober2012Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2012 [Member] | Margin [Member]                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | (1,100,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= pny_MarginMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeOfRegulatoryStaffOctober2012Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2013 [Member]                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Return on Equity, Percentage                                                                                      | 11.30%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office Of Regulatory Staff October 2013 [Member] | Margin [Member]                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | (100,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= pny_MarginMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office of Regulatory Staff October 2014 [Member]                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Return on Equity, Percentage                                                                                      | 10.20%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Settlement With Office of Regulatory Staff October 2014 [Member] | Margin [Member]                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | (2,900,000)us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= pny_MarginMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Environmental costs | Settlement With Office Of Regulatory Staff October 2013 [Member]                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 1 year                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Oct. 31,  2014                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 200,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeOfRegulatoryStaffOctober2013Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Environmental costs | Settlement With Office of Regulatory Staff October 2014 [Member]                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 1 year                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Oct. 31,  2015                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            | 100,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 100,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| PSCSC [Member] | Robeson LNG Development Cost [Member] | Settlement With Office of Regulatory Staff October 2014 [Member]                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 12 months                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Oct. 31,  2015                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets, Current                                                                                                                   | 500,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_SettlementWithOfficeofRegulatoryStaffOctober2014Member/ us-gaap_RegulatoryAgencyAxis= pny_PublicServiceCommissionofSouthCarolinaMember/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member]                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Flowed Through To Customers                                                                       | 75.00%pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Percentage Of Net Secondary Market Margins Retained                                                                                          | 25.00%pny_PercentageOfNetSecondaryMarketMarginsRetained/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Annual Incentive Cap On Gains And Losses                                                                                                     | 1,600,000.0pny_AnnualIncentiveCapOnGainsAndLosses/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Collection Nashville Franchise Fee [Member]                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Denied Franchise Fees                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 | 1,500,000pny_DeniedFranchiseFees/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_CollectionNashvilleFranchiseFeeMember/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                   |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 | 2,900,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_CollectionNashvilleFranchiseFeeMember/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Operations and maintenance                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               | (500,000)us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_CollectionNashvilleFranchiseFeeMember/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember | 1,500,000us-gaap_UtilitiesOperatingExpenseMaintenanceAndOperations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_CollectionNashvilleFranchiseFeeMember/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Actual Cost Adjustment [Member] | Subsequent Event [Member]                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | In December 2014, we filed an annual report for the twelve months ended June 30, 2013 with the TRA that reflected the transactions in the deferred gas cost account for the ACA mechanism. We are waiting on a ruling from the TRA at this time.                                                                                                                              |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Adjustment Filed August 2013 [Member]                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 | 3,700,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_AdjustmentFiledAugust2013Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Expense Related to Actual Cost Adjustment                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 | 1,700,000pny_ExpenseRelatedtoActualCostAdjustment/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_AdjustmentFiledAugust2013Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | TRA Settlement December 2014 [Member] | Subsequent Event [Member]                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   | 2,000,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_TRASettlementDecember2014Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember/ us-gaap_SubsequentEventTypeAxis= us-gaap_SubsequentEventMember |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   | In November 2014, we filed a joint settlement agreement with the TRA and the Tennessee Attorney General's Consumer Advocate and Protection Division (CAD) in which the parties agreed that we may include in our next ACA filing prior period adjustments totaling $2 million in lieu of the $3.7 million as originally petitioned. In December 2014, the TRA approved the settlement agreement, and we included the stipulated $2 million of prior period adjustments in the filed ACA annual report for the twelve-month period ended June 30, 2013. |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | General Rate Application Settlement 2012 [Member]                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Return on Equity, Percentage                                                                                      | 10.20%us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Recovery Of Fixed Charges Cost Allocations                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   | 37.00%pny_RecoveryOfFixedChargesCostAllocations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember | 29.00%pny_RecoveryOfFixedChargesCostAllocations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember |
| Recovery Of Volumetric Charges Cost Allocations                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   | 63.00%pny_RecoveryOfVolumetricChargesCostAllocations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember | 71.00%pny_RecoveryOfVolumetricChargesCostAllocations/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember |
| Tennessee Regulatory Authority [Member] | General Rate Application Settlement 2012 [Member] | Sales [Member]                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 11,900,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Percentage                                                                              | 6.30%us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage/ us-gaap_IncomeStatementLocationAxis= us-gaap_SalesMember/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Tennessee IMR Petition August 2013 [Member]                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 | 13,100,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_TennesseeIMRPetitionAugust2013Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Tennessee IMR Settlement 2013 [Member]                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Approved Rate Increase (Decrease), Amount                                                                                  | 13,100,000us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_TennesseeIMRSettlement2013Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | TRA IMR Rate Adjustment Petition Filed December 2014 [Member] | Subsequent Event [Member]          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 6,500,000us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_TRAPetitionFiledIMRDecember2014Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember/ us-gaap_SubsequentEventTypeAxis= us-gaap_SubsequentEventMember                                                                              |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | In December 2014, we filed a petition with the TRA seeking authority to collect an additional $6.5 million in annual IMR margin revenues effective January 2015 based on $54 million of capital investments in integrity and safety projects over the twelve-month period ending October 31, 2014. We are waiting on a ruling from the TRA at this time.                           |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | TRA Petition to Amortize and Refund Customers for Excess Deferred Taxes [Member]                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Requested Rate Increase (Decrease), Amount                                                                                 | (4,700,000)us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_TRAPetitiontoAmortizeandRefundCustomersforExcessDeferredTaxesMember/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Tennessee CNG Rider Petition September 2014 [Member] | Subsequent Event [Member]                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Public Utilities, Disclosure of Rate Matters                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       | In September 2014, we filed a petition with the TRA seeking authority to implement a compressed natural gas infrastructure rider to recover the costs of our capital investments in infrastructure and equipment associated with this alternative motor vehicle transportation fuel. We proposed that the tariff rider be effective October 1, 2014 with an initial rate adjustment on November 1, 2014 based on capital expenditures incurred through June 2014 and for rates to be updated annually outside of general rate cases for the return of and on these capital investments. In November 2014, the TRA consolidated this docket with a separate petition we filed seeking modifications to our tariff regarding service to customers using natural gas as a motor fuel. The TRA suspended the proposed tariffs through February 9, 2015. A hearing on this matter has been scheduled for January 12, 2015. |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Tennessee Regulatory Authority [Member] | Environmental costs | General Rate Application Settlement 2012 [Member]                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 8 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   | 2,000,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember |   |
| Tennessee Regulatory Authority [Member] | Other Regulatory Assets (Liabilities) [Member] | General Rate Application Settlement 2012 [Member] |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Approved [Abstract]**                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Amortization Time Period For Specified Expenses                                                                                              | 8 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Noncurrent Asset, End Date for Recovery                                                                                           | Feb. 28,  2020                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| **Public Utilities, Rate Matters, Requested [Abstract]**                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |
| Regulatory Assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                          |                                                                                                                                                 |                                                                               |                                                                                                                                              |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                 |   |   |   |   |   |   | 1,000,000us-gaap_RegulatoryAssets/ us-gaap_PublicUtilitiesRegulatoryProceedingAxis= pny_GeneralRateApplicationSettlement2012Member/ us-gaap_RegulatoryAgencyAxis= pny_TennesseeRegulatoryAuthorityMember/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember |   |

| X                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Time period allowed by the commission to amortize expenses.
+ References
No definition available.
+ Details**Name:**pny_AmortizationTimePeriodForSpecifiedExpenses**Namespace Prefix:**pny_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of net margins in secondary market transactions flowed through to jurisdictional customers in rates.
+ References
No definition available.
+ Details**Name:**pny_AmountOfNetSecondaryMarketMarginsFlowedThroughToJurisdictionalCustomers**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of net secondary market margins retained by Piedmont.
+ References
No definition available.
+ Details**Name:**pny_AmountOfNetSecondaryMarketMarginsRetained**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Annual incentive cap on gains and (losses) under the Tennessee Incentive Plan (TIP).
+ References
No definition available.
+ Details**Name:**pny_AnnualIncentiveCapOnGainsAndLosses**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The annual average cost increase % in our approved rates since our last general rate case proceeding.
+ References
No definition available.
+ Details**Name:**pny_ApprovedAnnualAverageRevenuePercentageIncreaseFromLastRateCase**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of the Company's capital investments in integrity and safety projects.
+ References
No definition available.
+ Details**Name:**pny_CapitalInvestmentsInIntegrityandSafetyProjects**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Time period allowed by the NCUC over which operations and maintenance expense can be deferred for Eastern NC.
+ References
No definition available.
+ Details**Name:**pny_DeferralTimePeriodOfOperationAndMaintenanceExpense**Namespace Prefix:**pny_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
In April 2010 the TRA passed a motion to deny collection of a portion of the uncollected franchise fees. In October 2011, the TRA issued an order denying recovery of the franchise fees consistent with the April motion. As the franchise fees were denied by the TRA, we recorded the franchise fees in operations and maintenance expenses. In November 2011, we filed for reconsideration on this ruling, which was granted.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Expense recorded for deferred gas cost that will not be included in the actual cost adjustment (ACA) settlement with the regulatory agency.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Interest accrued on the maximum deferral amount allowed by the regulatory commission.
+ References
No definition available.
+ Details**Name:**pny_InterestAccruedOnDeferredExpenses**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                    |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Point band change limit above or below the current allowed rate of return on equity.
+ References
No definition available.
+ Details**Name:**pny_MaximumUtilityRateofReturnChangeAllowedUnderRSA**Namespace Prefix:**pny_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Frequency that Piedmont is required to provide reporting of the operational feasibility for the area served by the natural gas serviced by the facilities built by general obligation bonds in eastern NC.
+ References
No definition available.
+ Details**Name:**pny_OperationalFeasibilityAssessmentTimePeriod**Namespace Prefix:**pny_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Overall rate base, including approved updated and increased rates and charges.
+ References
No definition available.
+ Details**Name:**pny_OverallRateBaseWithApprovedRatesAndCharges**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of gas costs approved for recovery after review by regulatory authority.
+ References
No definition available.
+ Details**Name:**pny_PercentageOfAllowedRecoveryForGasCosts**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of net margins in secondary market transactions flowed through to jurisdictional customers in rates.
+ References
No definition available.
+ Details**Name:**pny_PercentageOfNetSecondaryMarketMarginsFlowedThroughToCustomers**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of net secondary market margins retained by Piedmont.
+ References
No definition available.
+ Details**Name:**pny_PercentageOfNetSecondaryMarketMarginsRetained**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of public utility's approved limit for debt and/or equity securities as permitted by its Shelf Registration.
+ References
No definition available.
+ Details**Name:**pny_PublicUtilitiesApprovedDebtEquitySecuritiesLimitAmount**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of public utility's return on investment
+ References
No definition available.
+ Details**Name:**pny_PublicUtilitiesApprovedReturnonInvestmentPercentage**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cost allocations related to the recovery of fixed charges.
+ References
No definition available.
+ Details**Name:**pny_RecoveryOfFixedChargesCostAllocations**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cost allocations related to the recovery of volumetric charges.
+ References
No definition available.
+ Details**Name:**pny_RecoveryOfVolumetricChargesCostAllocations**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of capital costs, currently held in "Plant held for future use" in the Consolidated Balance Sheets. We are seeking authority from the regulatory commission to transfer costs to a deferred regulatory account in our general rate application.
+ References
No definition available.
+ Details**Name:**pny_RequestTransferPlantHeldForFutureUseToDeferredRegulatoryAsset**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
General obligation bond issued by state general assembly or regulatory commission for the purpose of providing grants, loans, or other financing for the cost of constructing natural gas facilities.
+ References
No definition available.
+ Details**Name:**pny_StateBondIssuanceAmount**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Our gas cost hedging plan's targeted percentage of annualized normalized sales volumes for jurisdiction.
+ References
No definition available.
+ Details**Name:**pny_TargetPercentageNormalizedSales**Namespace Prefix:**pny_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total amount of margin generated from secondary market activity.
+ References
No definition available.
+ Details**Name:**pny_TotalAmountOfMarginGeneratedFromSecondaryMarketActivity**Namespace Prefix:**pny_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585
+ Details**Name:**us-gaap_PaymentsToAcquirePropertyPlantAndEquipment**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of public utility's approved equity to capital, including debt and equity.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of public utility's approved rate increase (decrease) by regulatory agency.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of public utility's approved rate increase (decrease) by regulatory agency.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of public utility's approved return on equity.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Describes the general scope of regulation, including which regulatory bodies are officially authorized to oversee operations.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section 15 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6499301&loc=d3e40412-110365
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Describes all of the specific events that have or may impact rates and amortization of regulatory assets and liabilities (for example, pending or recently concluded regulatory proceedings, environmental requirements). Specifics may include quantifications related to rates, costs, and earnings. Events may relate to rate moratoriums or price caps.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesDisclosureOfRateMatters**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_PublicUtilitiesRateMattersApprovedAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_PublicUtilitiesRateMattersRequestedAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of public utility's requested rate increase (decrease) with regulatory agency.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382
+ Details**Name:**us-gaap_RegulatoryAssets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382
+ Details**Name:**us-gaap_RegulatoryAssetsCurrent**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
End date for recovery of the regulatory noncurrent asset, in CCYY-MM-DD format.
+ References
No definition available.
+ Details**Name:**us-gaap_RegulatoryNoncurrentAssetEndDateForRecovery**Namespace Prefix:**us-gaap_**Data Type:**xbrli:dateItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of operating expense for routine plant maintenance, repairs and operations of regulated operation.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688
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| X                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAgencyAxis=pny_NorthCarolinaUtilitiesCommissionMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAgencyAxis=pny_PublicServiceCommissionofSouthCarolinaMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAgencyAxis=pny_TennesseeRegulatoryAuthorityMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAssetAxis=pny_DeferredOperationsAndMaintenanceExpensesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAssetAxis=pny_DeferredPipelineIntegrityExpensesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAssetAxis=pny_RobesonLngDevelopmentCostMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RegulatoryAssetAxis=us-gaap_EnvironmentalRestorationCostsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_NC**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
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