| **Summary Of Significant Accounting Policies (Details) (USD $)**                                    | 3 Months Ended                                                                                                                                                                                     |                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | $ 12,595,000us-gaap_RegulatoryAssetsCurrent                                                                                                                                                        | $ 29,088,000us-gaap_RegulatoryAssetsCurrent                                                                                                                           |
| Regulatory assets - noncurrent                                                                      | 184,092,000us-gaap_RegulatoryAssetsNoncurrent                                                                                                                                                      | 184,779,000us-gaap_RegulatoryAssetsNoncurrent                                                                                                                         |
| Regulatory assets, Total                                                                            | 196,687,000us-gaap_RegulatoryAssets                                                                                                                                                                | 213,867,000us-gaap_RegulatoryAssets                                                                                                                                   |
| **Regulatory Liabilities [Line Items]**                                                             |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory liabilities - current                                                                    | 77,402,000us-gaap_RegulatoryLiabilityCurrent                                                                                                                                                       | 46,231,000us-gaap_RegulatoryLiabilityCurrent                                                                                                                          |
| Regulatory liabilities - noncurrent                                                                 | 568,163,000us-gaap_RegulatoryLiabilityNoncurrent                                                                                                                                                   | 558,598,000us-gaap_RegulatoryLiabilityNoncurrent                                                                                                                      |
| Regulatory liabilities, Total                                                                       | 645,565,000us-gaap_RegulatoryLiabilities                                                                                                                                                           | 604,829,000us-gaap_RegulatoryLiabilities                                                                                                                              |
| Amount Due To Customers [Member]                                                                    |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Liabilities [Line Items]**                                                             |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory liabilities - current                                                                    | 77,402,000us-gaap_RegulatoryLiabilityCurrent/ us-gaap_RegulatoryLiabilityAxis= pny_AmountDueToCustomersMember                                                                                      | 46,231,000us-gaap_RegulatoryLiabilityCurrent/ us-gaap_RegulatoryLiabilityAxis= pny_AmountDueToCustomersMember                                                         |
| Regulatory Cost of Removal [Member]                                                                 |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Liabilities [Line Items]**                                                             |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory liabilities - noncurrent                                                                 | 510,940,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= us-gaap_AssetRetirementObligationCostsMember                                                                    | 506,574,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= us-gaap_AssetRetirementObligationCostsMember                                       |
| Deferred Income Taxes [Member]                                                                      |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Liabilities [Line Items]**                                                             |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory liabilities - noncurrent                                                                 | 57,131,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= us-gaap_DeferredIncomeTaxChargesMember                                                                           | 51,930,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= us-gaap_DeferredIncomeTaxChargesMember                                              |
| Amounts Not Yet Recognized As Component Of Pension and Other Post Retirement Benefit Costs [Member] |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Liabilities [Line Items]**                                                             |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory liabilities - noncurrent                                                                 | 92,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= pny_AmountsNotYetRecognizedAsComponentOfPensionAndOtherPostRetirementBenefitCostsMember                              | 94,000us-gaap_RegulatoryLiabilityNoncurrent/ us-gaap_RegulatoryLiabilityAxis= pny_AmountsNotYetRecognizedAsComponentOfPensionAndOtherPostRetirementBenefitCostsMember |
| Unamortized Debt Expense [Member]                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 1,516,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_UnamortizedDebtExpenseMember                                                                                            | 1,490,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_UnamortizedDebtExpenseMember                                                               |
| Regulatory assets - noncurrent                                                                      | 15,004,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_UnamortizedDebtExpenseMember                                                                                        | 15,402,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_UnamortizedDebtExpenseMember                                                           |
| Amounts Due From Customers [Member]                                                                 |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 338,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_AmountsDueFromCustomersMember                                                                                             | 16,108,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_AmountsDueFromCustomersMember                                                             |
| Environmental Costs [Member]                                                                        |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 1,554,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                                 | 1,568,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                    |
| Regulatory assets - noncurrent                                                                      | 6,091,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                                              | 6,470,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_EnvironmentalRestorationCostsMember                                                 |
| Deferred Operations And Maintenance Expenses [Member]                                               |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 916,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                            | 916,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                               |
| Regulatory assets - noncurrent                                                                      | 4,528,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                                                       | 4,721,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredOperationsAndMaintenanceExpensesMember                                          |
| Deferred Pipeline Integrity Expenses [Member]                                                       |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 3,470,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                                 | 3,470,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                    |
| Regulatory assets - noncurrent                                                                      | 25,407,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                                             | 24,694,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPipelineIntegrityExpensesMember                                                |
| Deferred Pension and Other Retirement Benefit Costs [Member]                                        |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 2,757,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPensionAndOtherRetirementBenefitCostsMember                                                                     | 2,769,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPensionAndOtherRetirementBenefitCostsMember                                        |
| Regulatory assets - noncurrent                                                                      | 19,929,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPensionAndOtherRetirementBenefitCostsMember                                                                 | 18,799,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_DeferredPensionAndOtherRetirementBenefitCostsMember                                    |
| Amounts Not Yet Recognized As Component Of Pension and Other Post Retirement Benefit Costs [Member] |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - noncurrent                                                                      | 92,676,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_AmountsNotYetRecognizedAsComponentOfPensionAndOtherPostRetirementBenefitCostsMember                                 | 94,265,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_AmountsNotYetRecognizedAsComponentOfPensionAndOtherPostRetirementBenefitCostsMember    |
| Regulatory Cost of Removal [Member]                                                                 |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - noncurrent                                                                      | 18,509,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_AssetRetirementObligationCostsMember                                                                            | 18,275,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_AssetRetirementObligationCostsMember                                               |
| Robeson LNG Development Cost [Member]                                                               |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 783,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                                                           | 917,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                              |
| Regulatory assets - noncurrent                                                                      | 413,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                                                        | 509,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= pny_RobesonLngDevelopmentCostMember                                                           |
| Other [Member]                                                                                      |                                                                                                                                                                                               |                                                                                                                                                                  |
| **Regulatory Asset [Line Items]**                                                                   |                                                                                                                                                                                               |                                                                                                                                                                  |
| Regulatory assets - current                                                                         | 1,261,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                                                              | 1,850,000us-gaap_RegulatoryAssetsCurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                                 |
| Regulatory assets - noncurrent                                                                      | 1,535,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                                                           | 1,644,000us-gaap_RegulatoryAssetsNoncurrent/ us-gaap_RegulatoryAssetAxis= us-gaap_OtherRegulatoryAssetsLiabilitiesMember                                              |
| Accounting Standards Update 2013-11 [Member]                                                        |                                                                                                                                                                                               |                                                                                                                                                                  |
| **New Accounting Pronouncements or Change in Accounting Principle [Line Items]**                    |                                                                                                                                                                                               |                                                                                                                                                                  |
| New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification  | $ 0us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification/ us-gaap_AdjustmentsForNewAccountingPronouncementsAxis= pny_AccountingStandardsUpdate201311Member |                                                                                                                                                                  |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.
+ References
No definition available.
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| X                                                                                                                                                            |
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| 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
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| 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
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.
+ 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
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory liability as itemized in a table of regulatory liabilities 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 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities 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 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
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