Derivative Instruments - Effect of Interest Rate Swaps on Consolidated Statements of Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Effect of Derivatives on Statement of Operations and Comprehensive Income:
Realized gains (losses) on interest rate swaps	$ (224,272)	[1],[2]	$ (231,849)	[1],[2]	$ (665,614)	[1],[2]	$ (654,757)	[1],[2]
Gain (loss) on termination of interest rate swaps					(2,385)
Unrealized gains (losses) on interest rate swaps	$ (104,197)		$ (1,505,333)		$ (373,773)		$ (1,802,968)

[1] Interest expense related to the Company's interest rate swaps is recorded in Realized gains 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 Comprehensive Income as realized gains (losses) on interest rate swaps.