Rate and Regulatory Matters (Notes)	3 Months Ended
Mar. 31, 2017
Public Utilities, Rate Matters [Abstract]
Public Utilities, Disclosure of Rate Matters [Text Block]	RATE AND REGULATORY MATTERS Rate Case Settlement Filing On January 23, 2017, we filed for Federal Energy Regulatory Commission (FERC) approval a Stipulation and Settlement Agreement (Settlement) and were assigned Docket No. RP17-346. The Settlement specified an annual cost of service of $440 million and established a new general system firm Rate Schedule TF-1 (Large Customer) demand rate of $0.39294/Dth with a $0.00832 commodity rate (Phase 1) and a demand rate of $0.39033/Dth with a $0.00832 commodity rate (Phase 2). Phase 1 rates become effective January 1, 2018, with Phase 2 rates becoming effective October 1, 2018. The annual cost of service does not change from Phase 1 to Phase 2, but the Phase 2 rates reflect the termination of fifteen-year levelized contracts that will now become Rate Schedule TF-1 (Large Customer) contracts. Provisions were included in the Settlement that we can file a general rate case to place new rates into effect after October 1, 2018, and that a general rate case must be filed for new rates to become effective no later than January 1, 2023. Due to the resignation of one of the commissioners, the FERC has been left without a quorum since February 4, 2017. This lack of quorum has left FERC unable to formally approve the Settlement. In response, on March 29, 2017, we filed tariff records with the FERC to extend our requirement to file an NGA section 4 general rate case "by not later than July 1, 2017" (as required in our prior Settlement in Docket No. RP12-490 and our pending 2017 Settlement in RP 17-346). These tariff records also provide a means to place the rate reductions of the 2017 Settlement into effect commencing January 1, 2018 until a quorum at FERC is restored and can formally approve the Settlement. This new filing was assigned Docket No. RP17-567. On April 12, 2017, the FERC issued an order accepting the tariff records effective May 1, 2017.

RATE AND REGULATORY MATTERS

Rate Case Settlement Filing

On January 23, 2017, we filed for Federal Energy Regulatory Commission (FERC) approval a Stipulation and Settlement Agreement (Settlement) and were assigned Docket No. RP17-346. The Settlement specified an annual cost of service of $440 million and established a new general system firm Rate Schedule TF-1 (Large Customer) demand rate of $0.39294/Dth with a $0.00832 commodity rate (Phase 1) and a demand rate of $0.39033/Dth with a $0.00832 commodity rate (Phase 2). Phase 1 rates become effective January 1, 2018, with Phase 2 rates becoming effective October 1, 2018. The annual cost of service does not change from Phase 1 to Phase 2, but the Phase 2 rates reflect the termination of fifteen-year levelized contracts that will now become Rate Schedule TF-1 (Large Customer) contracts. Provisions were included in the Settlement that we can file a general rate case to place new rates into effect after October 1, 2018, and that a general rate case must be filed for new rates to become effective no later than January 1, 2023.

Due to the resignation of one of the commissioners, the FERC has been left without a quorum since February 4, 2017. This lack of quorum has left FERC unable to formally approve the Settlement. In response, on March 29, 2017, we filed tariff records with the FERC to extend our requirement to file an NGA section 4 general rate case "by not later than July 1, 2017" (as required in our prior Settlement in Docket No. RP12-490 and our pending 2017 Settlement in RP 17-346). These tariff records also provide a means to place the rate reductions of the 2017 Settlement into effect commencing January 1, 2018 until a quorum at FERC is restored and can formally approve the Settlement. This new filing was assigned Docket No. RP17-567. On April 12, 2017, the FERC issued an order accepting the tariff records effective May 1, 2017.