Derivatives - Location and Information of Derivatives (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss)	[1]	$ (246,105)	$ 8,099
Unrealized loss on derivatives		(89,058)	(216,338)
Total		(335,163)	(208,239)
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total		(336,285)	(208,236)
Interest rate swap contracts | Realized loss on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss)		(226,754)	48,931
Interest income		7,449	4,178
Interest expense		(26,991)	(44,919)
Interest rate swap contracts | Unrealized gain (loss) on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss on derivatives		(89,989)	(216,426)
Futures Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total		0	(3)
Futures Contracts | Realized loss on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss)		0	(91)
Futures Contracts | Unrealized gain (loss) on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss on derivatives		0	88
Basis swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total		1,122	0
Basis swap contracts | Realized loss on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Interest income		472	0
Interest expense		(281)	0
Basis swap contracts | Unrealized gain (loss) on derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss on derivatives		$ 931	$ 0

[1] Interest expense related to our interest rate swap contracts is recorded as realized loss on derivatives on the condensed consolidated statements of operations. For additional information, see Note 9 to the condensed consolidated financial statements.