Derivatives (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Values of Derivative Instruments
Derivative Assets	$ 69,809	$ 83,780
Derivative Liabilities	74,356	82,323
Derivatives designated as hedging instruments
Fair Values of Derivative Instruments
Notional Amount	48,365	131,391
Derivative Assets	0	4,325
Derivative Liabilities	6,793	5,976
Derivatives designated as hedging instruments | Interest rate swaps on certificates of deposit
Fair Values of Derivative Instruments
Notional Amount	48,365	48,365
Derivative Assets	0	0
Derivative Liabilities	6,793	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	9,170,134	8,507,660
Derivative Assets	69,809	79,455
Derivative Liabilities	67,563	76,347
Derivatives not designated as hedging instruments | Interest rate swaps and options
Fair Values of Derivative Instruments
Notional Amount	7,831,456	7,668,482
Derivative Assets	61,586	67,578
Derivative Liabilities	60,204	65,131
Derivatives not designated as hedging instruments | Foreign exchange contracts
Fair Values of Derivative Instruments
Notional Amount	1,267,282	767,764
Derivative Assets	8,220	11,874
Derivative Liabilities	7,357	11,213
Derivatives not designated as hedging instruments | RPAs
Fair Values of Derivative Instruments
Notional Amount	71,396	71,414
Derivative Assets	3	3
Derivative Liabilities	$ 2	$ 3