Fair Value of Financial Instruments Recorded basis and Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, Fair Value Disclosure		$ 3,737,729	$ 3,516,239
Mortgage loans held for investment, net, Fair Value Disclosure		27,439	39,700
Derivative assets		10,057	5,727
Repurchase Agreements, Fair Value Disclosure		3,055,069	3,013,110
FHLB advances, Fair Value Disclosure		255,000	0
Non-recourse collateralized financing, Fair Value Disclosure		8,581	10,786
Derivative liabilities, fair value disclosure		63,708	35,898
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, Fair Value Disclosure		3,737,729	3,516,239
Mortgage loans held for investment, net, Fair Value Disclosure	[1]	24,064	35,024
Derivative assets		10,057	5,727
Repurchase Agreements, Fair Value Disclosure	[2]	3,055,069	3,013,110
FHLB advances, Fair Value Disclosure	[2]	255,000	0
Non-recourse collateralized financing, Fair Value Disclosure	[1]	8,240	10,366
Derivative liabilities, fair value disclosure		$ 63,708	$ 35,898

[1] The Company determines the fair value of its mortgage loans held for investment, net and its non-recourse collateralized financing using internally developed cash flow models with inputs similar to those used to estimate fair value of the Company's Level 3 non-Agency MBS.

[2] The carrying value of repurchase agreements and FHLB advances generally approximates fair value due to their short term maturities