Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Mar. 31, 2016
Dec. 31, 2015
Derivatives, Fair Value [Line Items]        
Available-for-sale securities, at fair value $ 17,318,697 $ 13,128,857    
Mortgage servicing rights, at fair value 747,580 693,815 $ 446,170 $ 493,688
Interest-Only-Strip [Member]        
Derivatives, Fair Value [Line Items]        
Available-for-sale securities, at fair value $ 67,598 $ 71,084