Derivative Instruments - Effect on Statement of Operations and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Effect of derivatives on statement of operations and comprehensive income [Line Items]
Realized gains (loss) recognized on interest rate swaps	$ (227,638)	[1]	$ (231,849)	[1]	$ (216,760)	[1]	$ (206,148)	[1]	$ (190,098)	[1]	$ (188,636)	[1]	$ (175,535)	[1]	$ (180,838)	[1]	$ (882,395)	[1],[2]	$ (735,107)	[1],[2]	$ (719,803)	[1],[2]
Unrealized gain (loss) on interest rate swaps	$ (12,139)		$ (1,505,333)		$ (466,943)		$ 169,308		$ 839,191		$ (448,253)		$ (593,038)		$ (116,732)		$ (1,815,107)		$ (318,832)		$ 349,521

[1] Interest expense related to the Company's interest rate swaps is recorded in Realized losses on interest rate swaps on the Consolidated Statements of Operations and Comprehensive Income (Loss).

[2] Net interest payments on interest rate swaps is presented in the Company's Consolidated Statements of Operations and Comprehensive Income (Loss) as realized gains (losses) on interest rate swaps.