Derivatives and other Hedging Instruments - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Other Purchase Commitment	Dec. 31, 2012 Other Purchase Commitment	Dec. 31, 2013 Eurodollar Future
Derivative [Line Items]
Estimated amount related to derivatives reclassified to interest expense during the next 12 months	$ 82,182
The weighted-average remaining term of swaps	24 months
Fair value of all futures contracts, liability				25,585
Derivatives		(658)	3,305
Maximum leverage ratio the Company can reach before it could be in default of one of its derivative obligations	1000.00%
Fair value of derivatives in net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to agreements				125,133
Loss on derivative instruments, net	(69,715)			(33,298)
Unrealized gain (loss) on interest rate swaps	(68,205)			(25,585)
Notional Amount				$ 1,000