| **Regulatory Matters**                               | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  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| **Public Utilities, General Disclosures [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| Regulatory Matters                                   | Regulatory MattersRate Regulated Basis of AccountingRegulatory assets and liabilities in the Condensed Consolidated Balance Sheets as of July 31, 2016 and October 31, 2015 are as follows.In thousandsJuly 31, 2016 October 31, 2015Regulatory Assets:   Current:   Unamortized debt expense on reacquired debt$238 $238Amounts due from customers34,621 —Environmental costs1,516 1,513Deferred operations and maintenance expenses889 847Deferred pipeline integrity expenses3,470 3,470Deferred pension and other retirement benefit costs2,757 2,757Robeson liquefied natural gas (LNG) development costs223 381Derivatives - gas supply contracts held for utility operations33,300 —Other1,406 1,730Total current78,420 10,936Noncurrent:   Unamortized debt expense on reacquired debt4,488 4,666Environmental costs3,989 5,107Deferred operations and maintenance expenses3,325 3,997Deferred pipeline integrity expenses31,533 29,824Deferred pension and other retirement benefit costs17,509 17,861Amounts not yet recognized as a component of pension and other retirement benefit costs109,884 114,854Regulatory cost of removal asset19,925 19,087Robeson LNG development costs— 127Derivatives - gas supply contracts held for utility operations149,600 —Other871 1,203Total noncurrent341,124 196,726Total$419,544 $207,662Regulatory Liabilities:   Current:   Amounts due to customers$3,908 $13,367Noncurrent:   Regulatory cost of removal obligations533,844 521,478Deferred income taxes64,827 68,738Amounts not yet recognized as a component of pension and other retirement benefit costs78 85Total noncurrent598,749 590,301Total$602,657$603,668Rate Oversight and Rate and Regulatory ActionsNorth CarolinaIn November 2015, we filed a petition with the NCUC seeking authority, under the approved integrity management rider (IMR) mechanism, to change our rates effective December 1, 2015 to collect a total of $40.9 million in annual IMR margin revenues based on IMR-eligible capital investments in integrity and safety projects through September 30, 2015. In December 2015, the NCUC approved the requested IMR rate increase. In February 2016, the NCUC Public Staff filed their IMR audit report for the capital investment period through September 30, 2015, proposing an immaterial reduction in IMR margin for refund to customers, which we began recording in January 2016. In May 2016, we filed a petition to update our rates effective June 1, 2016 to collect an additional $7.4 million in annual IMR margin revenues from that approved by the NCUC in December 2015. The June 2016 rate adjustment was based on $74.9 million of IMR-eligible capital investments in integrity and safety projects over the six-month period ended March 31, 2016. In May 2016, the NCUC approved the requested IMR rate increase. In January 2016, we and Duke Energy filed a joint application with the NCUC seeking regulatory approval of the Acquisition. Subsequently, we, Duke Energy and the NCUC Public Staff reached an agreement of stipulation and settlement setting forth stipulations and conditions for approval of the proposed Acquisition, which was originally filed with the NCUC in June 2016. Among the stipulations contained in the agreement are:•Funding by the combined company of annual charitable contributions totaling at least $17.5 million in North Carolina during each of the four years after the Acquisition;•Commitment by the combined company of $7.5 million for low-income household energy assistance and workforce development programs in North Carolina during the first year after the Acquisition;•Exclusion of expenses related to the Acquisition, including severance costs, from customer bills;•Withdrawal of our March 2016 petition requesting approval of deferred accounting treatment for certain distribution integrity management program expenses; and•A one-time bill credit to our North Carolina customers collectively of $10 million.A hearing was held on July 18 and 19, 2016. On August 25, 2016, we, Duke Energy and the NCUC Public Staff filed a joint proposed order pursuant to the NCUC's procedural schedule. We are waiting on a ruling from the NCUC at this time.In March 2016, we filed a petition with the NCUC requesting approval of deferred accounting treatment for certain distribution integrity management program expenses. We proposed this accounting treatment as an extension of the regulatory asset accounting treatment approved by the NCUC in December 2004 for our transmission integrity management program expenses. In June 2016, we agreed to withdraw this deferral request upon the NCUC’s approval of the agreement of stipulation and settlement in the proceeding seeking approval of the Acquisition as discussed above and upon closing of the Acquisition.In August 2016, we filed testimony with the NCUC in support of our gas cost purchasing and accounting practices for the twelve months ended May 31, 2016. A hearing has been scheduled for October 3, 2016.South CarolinaIn June 2016, we filed testimony with the Public Service Commission of South Carolina (PSCSC) in support of our annual review of purchased gas adjustment and gas purchasing policies for the twelve months ended March 31, 2016. In June 2016, a settlement agreement with the Office of Regulatory Staff (ORS) was filed. A hearing was held on July 14, 2016. In August 2016, the PSCSC approved the settlement agreement finding that our gas purchasing policies were reasonable and prudent, that we properly adhered to the gas cost recovery provisions of our tariff and relevant PSCSC orders and that we managed our hedging program in a manner consistent with PSCSC orders.In June 2016, we filed with the PSCSC a quarterly monitoring report for the twelve months ended March 31, 2016 and a cost and revenue study under the Rate Stabilization Act requesting a change in rates. In August 2016, a settlement agreement was filed with the ORS stipulating an $8.3 million annual increase in margin based on a return on equity of 10.2%, effective November 1, 2016. We are waiting on a ruling from the PSCSC at this time.TennesseeIn February 2016, we filed an annual report for the twelve months ended June 30, 2015 with the TRA that reflected the transactions in the deferred gas cost account for the Actual Cost Adjustment (ACA) mechanism. In June 2016, the TRA approved the deferred gas cost account balances and issued its written order. In August 2016, we filed an annual report for the twelve months ended June 30, 2016 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.In August 2016, we filed an annual report with the TRA reflecting the shared gas cost savings from gains and losses derived from gas purchase benchmarking and secondary market transactions for the twelve months ended June 30, 2016 under the Tennessee Incentive Plan (TIP). We are waiting on a ruling from the TRA at this time.In July 2016, the TRA Staff filed its compliance audit report for operation of our Weather Normalization Adjustment (WNA) rider during the 2015 – 2016 heating season, concluding that we had correctly implemented the WNA rider in all material aspects. The TRA Staff identified an immaterial error that resulted in an under-collection of our WNA revenues and recommended a correcting adjustment through the ACA mechanism which we recorded in August 2016. In August 2016, the TRA approved and adopted the TRA Staff’s compliance audit report. |

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