Regulatory Matters (Details) (USD $)	12 Months Ended	3 Months Ended	1 Months Ended
	Oct. 31, 2014	Jan. 31, 2015	Sep. 30, 2014	Feb. 28, 2015
Public Utilities, Rate Matters, Approved [Abstract]
Regulatory assets	$ 29,088,000	$ 12,595,000
Robeson LNG Development Cost [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Regulatory assets	917,000	783,000
Environmental Restoration Costs [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Regulatory assets	1,568,000	1,554,000
NORTH CAROLINA
Public Utilities, Rate Matters, Approved [Abstract]
Capital Investments In Integrity and Safety Projects	241,900,000
TENNESSEE
Public Utilities, Rate Matters, Approved [Abstract]
Capital Investments In Integrity and Safety Projects	54,000,000
North Carolina Utilities Commission [Member] | NCUC Authorized IMR Adjustment January 2015 [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Public Utilities Approved Rate Increase (Decrease) Amount		26,600,000
Public Service Commission of South Carolina [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%
Public Service Commission of South Carolina [Member] | Settlement With Office of Regulatory Staff October 2014 [Member] | Robeson LNG Development Cost [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Regulatory assets	500,000
Amortization Time Period For Specified Expenses		1 year
Regulatory Current Asset, End Date for Recovery		10/31/2015
Public Service Commission of South Carolina [Member] | Settlement With Office of Regulatory Staff October 2014 [Member] | Environmental Restoration Costs [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Regulatory assets	100,000
Amortization Time Period For Specified Expenses		1 year
Regulatory Current Asset, End Date for Recovery		October 31, 2015
Tennessee Regulatory Authority [Member] | Adjustment Filed August 2013 [Member]
Public Utilities, Rate Matters, Requested [Abstract]
Public Utilities Requested Rate Increase (Decrease) Amount		3,700,000
Public Utilities, Rate Matters, Approved [Abstract]
Expense Related to Actual Cost Adjustment			1,700,000
Tennessee Regulatory Authority [Member] | Tennessee Requested ACA December 2014 [Member]
Public Utilities, Rate Matters, Requested [Abstract]
Public Utilities Requested Rate Increase (Decrease) Amount		2,000,000
Tennessee Regulatory Authority [Member] | TRA Approved ACA Adjustment January 2015 [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Public Utilities Approved Rate Increase (Decrease) Amount		2,000,000
Tennessee Regulatory Authority [Member] | Amortization And Refund For Excess Deferred Taxes [Member]
Public Utilities, Rate Matters, Requested [Abstract]
Public Utilities Requested Rate Increase (Decrease) Amount		(4,700,000)
Proposed Amortization Time Period For Specified Expenses		3 years
Tennessee Regulatory Authority [Member] | Tennessee Ruling Compressed Natural Gas February 2015 [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Deferral CNG Equipment In Utility Rate Base		4,700,000
Subsequent Event [Member] | Tennessee Regulatory Authority [Member] | TRA Approved IMR Adjustment February 2015 [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Public Utilities Approved Rate Increase (Decrease) Amount				6,500,000
Public Utilities, Disclosure of Rate Matters				In December 2014, we filed a petition with the TRA seeking authority to collect through adjusted rates 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 ended October 31, 2014. In January 2015, the TRA accepted and approved the requested IMR rate adjustment and issued its written order in February 2015.
Subsequent Event [Member] | Tennessee Regulatory Authority [Member] | Tennessee Ruling Compressed Natural Gas February 2015 [Member]
Public Utilities, Rate Matters, Approved [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 (CNG) 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. A hearing on this matter was held in January 2015. In February 2015, the TRA (1) denied approval of the proposed tariff rider, (2) ruled that our retail CNG motor fuel service should be unregulated and no longer provided under our regulated tariff, and (3) approved the proposed modification to our tariff providing natural gas for motor fuel purposes at customer premises. The TRA indicated that we may seek recovery of our prior investments in CNG equipment of $4.7 million since our last rate proceeding in utility rate base in our next general rate case proceeding as the investments were made in good faith under the assumption retail CNG motor fuel would be a regulated service. We are waiting on the TRA's written order.
Margin [Member] | Public Service Commission of South Carolina [Member] | Settlement With Office of Regulatory Staff October 2014 [Member]
Public Utilities, Rate Matters, Approved [Abstract]
Public Utilities Approved Rate Increase (Decrease) Amount		$ (2,900,000)