Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Derivatives, Fair Value [Line Items]    
Available-for-sale securities, at fair value $ 14,284,625 $ 7,825,320
Interest-Only-Strip [Member]    
Derivatives, Fair Value [Line Items]    
Available-for-sale securities, at fair value $ 50,132 $ 42,931