Schedule of Interest Rate Swap Agreements on Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Unrealized gain (loss) on interest rate swaps	$ (68,205)
Interest Rate Swap
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Beginning balance	(243,051)	(218,451)
Unrealized gain (loss) on interest rate swaps	15,030	(141,392)
Reclassification of net losses included in income statement	116,847	116,792
Ending balance	$ (111,174)	$ (243,051)