Schedule of Location of Derivatives on Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives Fair Value [Line Items]
Derivative assets	$ 27,151	$ 26,989
Derivative liabilities	244,591	167,607
Interest Rate Swaps and Swaptions | Derivative Assets
Derivatives Fair Value [Line Items]
Derivative assets	11,050	15,841
Futures Contracts | Derivative Assets
Derivatives Fair Value [Line Items]
Derivative assets		11,148
Futures Contracts | Derivative Liabilities
Derivatives Fair Value [Line Items]
Derivative liabilities	202,501	36,733
Forward Purchase Commitments - MBS | Derivative Assets
Derivatives Fair Value [Line Items]
Derivative assets	16,101
Forward Purchase Commitments - MBS | Derivative Liabilities
Derivatives Fair Value [Line Items]
Derivative liabilities	36	5,741
Interest Rate Swap | Derivative Liabilities
Derivatives Fair Value [Line Items]
Derivative liabilities	42,052	125,133
Forward Purchase Commitments - Mortgage Loans | Derivative Liabilities
Derivatives Fair Value [Line Items]
Derivative liabilities	$ 2