The Components of Loss on Derivative Instruments Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	$ (130,301)	$ 35,430	$ (252,501)	$ (61,445)
Interest Rate Swaps – Net Realized and Unrealized Gains
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	(4,227)	38,136	7,386	62,524
Interest Rate Swaptions
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	(8,202)	(1,304)	(11,492)	(3,983)
Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	(9,510)	(29,079)	(46,150)	(88,245)
Futures Contracts
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	(130,060)	37,405	(191,720)	(69,982)
Futures Contracts - Other Realized Losses
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	(2,721)		(25,394)
Mortgage Loan Purchase Commitments - Fair Value Adjustments
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	368		415
TBA Dollar Roll
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	20,512	22,370	68,568	68,813
TBA Dollar Rolls – Net Realized And Unrealized Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	17,528	(30,288)	(21,558)	(6,509)
Futures Contracts - Losses From Maturities
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	$ (13,989)	$ (1,810)	$ (32,556)	$ (24,063)