The Components of Loss on Derivative Instruments Net (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments	$ 64,085	$ (130,301)	$ (19,415)	$ (102,785)	$ (79,988)	$ 35,430	$ (55,260)	$ (41,615)	$ (188,416)	$ (141,433)	$ (69,715)
Interest Rate Swaps – Net Realized and Unrealized Gains
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									24,851	73,729	25,036
Interest Rate Swaptions
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									(12,597)	(15,520)
Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									(55,064)	(113,919)	(30,985)
Futures Contracts
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									(82,864)	(176,916)	(25,585)
Futures Contracts - Other Realized Losses
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									(45,836)	(29,423)	(33,298)
Mortgage Loan Purchase Commitments - Fair Value Adjustments
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									11	(2)
TBA Dollar Roll
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									83,397	92,008	5,605
TBA Dollar Rolls – Net Realized And Unrealized Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									(52,194)	$ 28,610	$ (10,488)
Futures Contracts - Losses From Maturities
Derivative Instruments Gain Loss [Line Items]
Net gain (loss) on derivative instruments									$ (48,120)