Segment Information (Reconciliation Of Total Segment Margin To Net Income (Loss) From Continuing Operations Before Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	5 Months Ended	12 Months Ended	7 Months Ended	12 Months Ended
	May 25, 2010 Predecessor [Member]	Dec. 31, 2009 Predecessor [Member]	Dec. 31, 2010 Successor [Member]	Dec. 31, 2011 Successor [Member]
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	$ (4,215)	$ 141,663	$ (4,176)	$ 74,084
Operation and maintenance	47,842	117,080	77,808	147,643
General and administrative, including related party	37,212	57,863	43,739	67,408
(Gain) loss on asset sales, net	303	(133,282)	213	(2,372)
Depreciation and amortization	41,784	100,098	75,967	168,684
Income from unconsolidated affiliates	(15,872)	(7,886)	(53,493)	(119,540)
Interest expense, net	34,541	77,665	48,251	102,474
Gains (Losses) on Restructuring of Debt	1,780	0	15,748	0
Other income and deductions, net	3,897	15,132	8,229	(17,309)
Total segment margin	$ 147,272	$ 368,333	$ 212,286	$ 421,072