Derivatives (Details) $ in Thousands	Jun. 30, 2017 USD ($) company	Dec. 31, 2016 USD ($)
Fair Values of Derivative Instruments
Derivative Assets	$ 79,764	$ 83,780
Derivative Liabilities	83,400	82,323
Derivatives designated as hedging instruments
Fair Values of Derivative Instruments
Notional Amount	42,566	131,391
Derivative Assets	0	4,325
Derivative Liabilities	6,686	5,976
Derivatives designated as hedging instruments | Interest rate swaps on certificates of deposit
Fair Values of Derivative Instruments
Notional Amount	42,566	48,365
Derivative Assets	0	0
Derivative Liabilities	6,686	5,976
Derivatives designated as hedging instruments | Foreign currency forward contracts
Fair Values of Derivative Instruments
Notional Amount	0	83,026
Derivative Assets	0	4,325
Derivative Liabilities	0	0
Derivatives not designated as hedging instruments
Fair Values of Derivative Instruments
Notional Amount	9,723,734	8,507,660
Derivative Assets	79,764	79,455
Derivative Liabilities	76,714	76,347
Derivatives not designated as hedging instruments | Interest rate swaps and options
Fair Values of Derivative Instruments
Notional Amount	8,172,811	7,668,482
Derivative Assets	64,254	67,578
Derivative Liabilities	63,551	65,131
Derivatives not designated as hedging instruments | Foreign exchange contracts
Fair Values of Derivative Instruments
Notional Amount	1,481,244	767,764
Derivative Assets	14,722	11,874
Derivative Liabilities	13,161	11,213
Derivatives not designated as hedging instruments | RPAs
Fair Values of Derivative Instruments
Notional Amount	69,679	71,414
Derivative Assets	2	3
Derivative Liabilities	2	3
Derivatives not designated as hedging instruments | Warrants
Fair Values of Derivative Instruments
Notional Amount	0	0
Derivative Assets	786	0
Derivative Liabilities	$ 0	$ 0
Number of public companies in which warrants are held | company	4