Investment in Unconsolidated Ventures (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Investment in Unconsolidated Ventures [Abstract]
Number of investments in unconsolidated joint ventures	5	5
Percentage ownership in purchase or sale of unconsolidated joint ventures (in hundredths)	10.00%		10.00%
Number of acquired investments in unconsolidated joint ventures	1.0000		1.0000
Aggregate sales price of interest sold			$ 14,300,000
Percentage ownership in unconsolidated joint ventures -lower range (in hundredths)	10.00%	20.00%
Percentage ownership in unconsolidated joint ventures -upper range (in hundredths)	20.00%	20.00%
Expense [Abstract]
Total operating expense	2,367,738,000	2,214,541,000	2,070,494,000
Interest income	3,538,000	2,238,000	2,354,000
Balance Sheet Data [Abstract]
Cash and cash equivalents	30,836,000	81,827,000	66,370,000	53,973,000
Property, plant and equipment, net	3,694,064,000	3,736,842,000
Other	109,934,000	98,973,000
Total assets	4,466,061,000	4,530,470,000
Long-term debt	2,350,971,000	2,498,620,000
Members' equity	250,958,000	129,344,000
Total liabilities and members' equity	4,466,061,000	4,530,470,000
Members' equity consists of [Abstract]
Cumulative net loss	(884,051,000)	(815,876,000)
Members' equity	250,958,000	129,344,000
Investment in Unconsolidated Ventures [Member]
Statement of Operations Data [Abstract]
Total revenue	154,964,000	84,689,000	108,711,000
Expense [Abstract]
Facility operating expense	103,611,000	54,766,000	66,507,000
Depreciation and amortization	23,923,000	12,730,000	15,725,000
Interest expense	27,072,000	13,153,000	19,616,000
Other expense	6,885,000	4,585,000	6,103,000
Total operating expense	161,491,000	85,234,000	107,951,000
Interest income	108,000	24,000	3,834,000
Net (loss) income	(6,419,000)	(521,000)	4,594,000
Balance Sheet Data [Abstract]
Cash and cash equivalents	15,255,000	3,077,000
Property, plant and equipment, net	1,012,941,000	323,492,000
Other	184,052,000	115,189,000
Total assets	1,212,248,000	441,758,000
Accounts payable and accrued expenses	61,199,000	46,589,000
Long-term debt	900,091,000	265,825,000
Members' equity	250,958,000	129,344,000
Total liabilities and members' equity	1,212,248,000	441,758,000
Members' equity consists of [Abstract]
Invested capital	403,625,000	265,243,000
Cumulative net loss	(25,810,000)	(19,391,000)
Cumulative distributions	(126,857,000)	(116,508,000)
Members' equity	$ 250,958,000	$ 129,344,000