Annual report pursuant to Section 13 and 15(d)

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

v3.3.1.900
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Derivatives, Fair Value [Line Items]    
Available-for-sale securities $ 7,825,320 $ 14,341,102
Interest-Only-Strip [Member]    
Derivatives, Fair Value [Line Items]    
Available-for-sale securities $ 42,931 $ 55,686