Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details)

v3.3.0.814
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2015
Dec. 31, 2014
Derivatives, Fair Value [Line Items]    
Available-for-sale securities, at fair value $ 11,433,195 $ 14,341,102
Interest-Only-Strip [Member]    
Derivatives, Fair Value [Line Items]    
Available-for-sale securities, at fair value $ 45,199 $ 55,686