CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2012 Successor [Member]	Sep. 30, 2012 Successor [Member]	Mar. 25, 2012 Predecessor [Member]	Sep. 30, 2011 Predecessor [Member]	Sep. 30, 2011 Predecessor [Member]
Operating revenues	$ 477,896	$ 990,078	$ 633,649	$ 617,211	$ 1,995,640
Operating expenses:
Cost of natural gas and other energy	180,733	374,220	311,270	304,535	1,045,742
Operating, maintenance and general	121,325	306,606	134,921	125,710	370,562
Depreciation and amortization	75,710	154,909	56,544	59,327	177,949
Revenue-related taxes	3,835	8,370	9,867	4,268	26,835
Taxes, other than on income and revenues	14,575	31,304	14,296	12,845	40,972
Total operating expenses	396,178	875,409	526,898	506,685	1,662,060
Operating income	81,718	114,669	106,751	110,526	333,580
Other income (expenses):
Interest expense	(34,639)	(96,323)	(50,407)	(54,925)	(165,429)
Earnings from unconsolidated investments	(1,065)	(381)	16,160	26,686	78,435
Other, net	(69)	122	284	191	557
Total other expenses, net	(35,773)	(96,582)	(33,963)	(28,048)	(86,437)
Income (loss) before income taxes	45,945	18,087	72,788	82,478	247,143
Income tax expense (benefit)	28,959	27,883	22,871	24,446	68,676
Net income (loss)	$ 16,986	$ (9,796)	$ 49,917	$ 58,032	$ 178,467