Derivative Instruments (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Components of unrealized net gains and net interest income
Change in fair value of Linked Transactions included in earnings			$ 0	$ 2,542
Legacy Non-Agency MBS
Components of unrealized net gains and net interest income
Interest income attributable to MBS underlying Linked Transactions	$ 66,779	$ 77,747	210,968	239,879
RPL/NPL MBS
Components of unrealized net gains and net interest income
Interest income attributable to MBS underlying Linked Transactions	23,651	97	65,264	800
CRT securities
Components of unrealized net gains and net interest income
Interest income attributable to MBS underlying Linked Transactions	$ 1,593	30	$ 4,477	30
Linked Transactions
Linked Repurchase Agreements
Balance					$ 1,519,593
Weighted Average Interest Rate (as a percent)					1.47%
Linked MBS
Fair Value					$ 1,917,813
Amortized Cost					1,913,276
Par/Current Face					$ 1,926,987
Weighted Average Coupon Rate (as a percent)					3.52%
Accrued interest receivable					$ 1,300
Accrued interest payable					1,100
Components of unrealized net gains and net interest income
Interest income attributable to MBS underlying Linked Transactions		6,625		11,591
Interest expense attributable to linked repurchase agreement borrowings underlying Linked Transactions		(2,246)		(3,719)
Change in fair value of Linked Transactions included in earnings		(1,820)		1,714
Unrealized net gains and net interest income from Linked Transactions		$ 2,559		$ 9,586
Linked Transactions | Within 30 days
Linked Repurchase Agreements
Balance					$ 1,514,393
Weighted Average Interest Rate (as a percent)					1.47%
Linked Transactions | Over 30 days to 90 days
Linked Repurchase Agreements
Balance					$ 5,200
Weighted Average Interest Rate (as a percent)					1.35%
Linked Transactions | Legacy Non-Agency MBS
Linked MBS
Fair Value					$ 66,382
Amortized Cost					61,658
Par/Current Face					$ 72,513
Weighted Average Coupon Rate (as a percent)					4.20%
Linked Transactions | RPL/NPL MBS
Linked MBS
Fair Value					$ 1,846,807
Amortized Cost					1,847,118
Par/Current Face					$ 1,849,974
Weighted Average Coupon Rate (as a percent)					3.49%
Linked Transactions | CRT securities
Linked MBS
Fair Value					$ 4,624
Amortized Cost					4,500
Par/Current Face					$ 4,500
Weighted Average Coupon Rate (as a percent)					4.56%