Schedule I Disclosures for Parent Company Only Schedule I, Derivatives Not Designated as Hedging Instruments Statement of Financial Performance and Financial Position Location (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ (55,383)	$ (28,505)	$ 45,837
Parent [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(55,383)	(28,505)	45,837
Parent [Member] | Interest Rate Swap [Member] | Unrealized Gain (Loss) on Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	(42,010)	(15,193)	55,653
Parent [Member] | Interest Rate Swap [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ (13,373)	$ (13,312)	$ (9,816)