CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012 Successor [Member]	Jun. 30, 2012 Successor [Member]	Mar. 25, 2012 Predecessor [Member]	Jun. 30, 2011 Predecessor [Member]	Jun. 30, 2011 Predecessor [Member]
Operating revenues	$ 472,470	$ 512,182	$ 633,649	$ 631,607	$ 1,378,429
Operating expenses:
Cost of natural gas and other energy	175,961	193,487	311,270	315,575	741,207
Operating, maintenance and general	124,248	185,281	134,921	123,858	244,852
Depreciation and amortization	74,476	79,199	56,544	59,295	118,622
Revenue-related taxes	4,142	4,535	9,867	5,200	22,567
Taxes, other than on income and revenues	14,604	16,729	14,296	12,657	28,127
Total operating expenses	393,431	479,231	526,898	516,585	1,155,375
Operating income	79,039	32,951	106,751	115,022	223,054
Other income (expenses):
Interest expense	(57,303)	(61,684)	(50,407)	(54,933)	(110,504)
Earnings from unconsolidated investments	672	684	16,160	25,048	51,749
Other, net	175	191	284	224	366
Total other expenses, net	(56,456)	(60,809)	(33,963)	(29,661)	(58,389)
Earnings (loss) before income taxes	22,583	(27,858)	72,788	85,361	164,665
Income tax expense (benefit)	10,858	(1,076)	22,871	25,588	44,230
Net earnings (loss)	$ 11,725	$ (26,782)	$ 49,917	$ 59,773	$ 120,435