Regulatory Matters	3 Months Ended
Dec. 31, 2015
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Matters	Regulatory Matters Following negotiations and other proceedings, on December 6, 2013, Distribution Corporation filed an agreement, also executed by the Department of Public Service and intervenors, extending existing rates through, at a minimum, September 30, 2015. Although customer rates were not changed, the parties agreed that the allowed rate of return on equity would be set, for ratemaking purposes, at 9.1%. Following conventional practice in New York, the agreement authorizes an “earnings sharing mechanism” (“ESM”). The ESM distributes earnings above the allowed rate of return as follows: from 9.5% to 10.5%, 50% would be allocated to shareholders, and 50% will be deferred for the benefit of customers; above 10.5%, 20% would be allocated to shareholders and 80% will be deferred for the benefit of customers. The agreement further authorizes, and rates reflect, an increase in Distribution Corporation’s pipeline replacement spending by $8.2 million per year of the agreement. The agreement contains other terms and conditions of service that are customary for settlement agreements recently approved by the NYPSC. A $7.5 million refund provision was passed back to ratepayers during 2014 after the NYPSC approved the settlement agreement without modification in an order issued on May 8, 2014. All significant terms of the agreement, including existing rates, continue in effect beyond September 30, 2015 until modified by the NYPSC. The agreement also states that nothing in the agreement precludes the parties from meeting to discuss extending the agreement on mutually acceptable terms, and presenting such extension to the NYPSC for approval. On May 22, 2015, Distribution Corporation filed with the NYPSC a Notice of Impending Settlement Discussions stating that settlement discussions would be scheduled in the near future, and that such discussions might include, among other things, the possible extension of the agreement on mutually acceptable terms, and on October 21, 2015, Distribution Corporation filed with the NYPSC a Supplemental Notice of Impending Settlement Discussions. In the event settlement is not reached, nothing prevents Distribution Corporation from continuing to operate under the existing agreement or from filing a rate case. FERC Rate Proceedings On November 13, 2015, FERC approved Supply Corporation's rate case settlement that extends Supply Corporation's current FERC-approved rate case settlement, requires a rate case filing no later than December 31, 2019 and prohibits any party from seeking to initiate a rate case proceeding before September 30, 2017. Prior to this new extension settlement, Supply Corporation had been otherwise required by its existing rate settlement to make a general rate filing no later than January 1, 2016. The new extension settlement provides, among other things, that Supply Corporation reduce its maximum reservation, capacity, demand and deliverability rates by 2% effective November 1, 2015, and further reduce those rates by an additional 2% on November 1, 2016. Pursuant to the new extension settlement, Supply Corporation also adopted a mechanism that allows it to recover, as a surcharge, certain pipeline safety and greenhouse gas costs it may incur as a result of new rules and regulations. Empire does not have a rate case currently on file with the FERC, but by order dated January 21, 2016, the FERC began a NGA Section 5 rate review of Empire's rates. By that order, Empire is required to file a Cost and Revenue Study within 75 days (by April 5, 2016).

Regulatory Matters

Following negotiations and other proceedings, on December 6, 2013, Distribution Corporation filed an agreement, also executed by the Department of Public Service and intervenors, extending existing rates through, at a minimum, September 30, 2015. Although customer rates were not changed, the parties agreed that the allowed rate of return on equity would be set, for ratemaking purposes, at 9.1%. Following conventional practice in New York, the agreement authorizes an “earnings sharing mechanism” (“ESM”). The ESM distributes earnings above the allowed rate of return as follows: from 9.5% to 10.5%, 50% would be allocated to shareholders, and 50% will be deferred for the benefit of customers; above 10.5%, 20% would be allocated to shareholders and 80% will be deferred for the benefit of customers. The agreement further authorizes, and rates reflect, an increase in Distribution Corporation’s pipeline replacement spending by $8.2 million per year of the agreement. The agreement contains other terms and conditions of service that are customary for settlement agreements recently approved by the NYPSC. A $7.5 million refund provision was passed back to ratepayers during 2014 after the NYPSC approved the settlement agreement without modification in an order issued on May 8, 2014. All significant terms of the agreement, including existing rates, continue in effect beyond September 30, 2015 until modified by the NYPSC. The agreement also states that nothing in the agreement precludes the parties from meeting to discuss extending the agreement on mutually acceptable terms, and presenting such extension to the NYPSC for approval. On May 22, 2015, Distribution Corporation filed with the NYPSC a Notice of Impending Settlement Discussions stating that settlement discussions would be scheduled in the near future, and that such discussions might include, among other things, the possible extension of the agreement on mutually acceptable terms, and on October 21, 2015, Distribution Corporation filed with the NYPSC a Supplemental Notice of Impending Settlement Discussions. In the event settlement is not reached, nothing prevents Distribution Corporation from continuing to operate under the existing agreement or from filing a rate case.

FERC Rate Proceedings

On November 13, 2015, FERC approved Supply Corporation's rate case settlement that extends Supply Corporation's current FERC-approved rate case settlement, requires a rate case filing no later than December 31, 2019 and prohibits any party from seeking to initiate a rate case proceeding before September 30, 2017. Prior to this new extension settlement, Supply Corporation had been otherwise required by its existing rate settlement to make a general rate filing no later than January 1, 2016. The new extension settlement provides, among other things, that Supply Corporation reduce its maximum reservation, capacity, demand and deliverability rates by 2% effective November 1, 2015, and further reduce those rates by an additional 2% on November 1, 2016. Pursuant to the new extension settlement, Supply Corporation also adopted a mechanism that allows it to recover, as a surcharge, certain pipeline safety and greenhouse gas costs it may incur as a result of new rules and regulations.

Empire does not have a rate case currently on file with the FERC, but by order dated January 21, 2016, the FERC began a NGA Section 5 rate review of Empire's rates. By that order, Empire is required to file a Cost and Revenue Study within 75 days (by April 5, 2016).