Derivatives (Details 2) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative liabilities	$ 74,356	$ 82,323
Derivative assets	69,809	83,780
Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	48,365	131,391
Derivative liabilities	6,793	5,976
Derivative assets	0	4,325
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	9,170,134	8,507,660
Derivative liabilities	67,563	76,347
Derivative assets	69,809	79,455
Interest rate swaps on certificates of deposit | Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	48,365	48,365
Derivative liabilities	6,793	5,976
Derivative assets	0	0
Foreign currency forward contracts | Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	0	83,026
Derivative liabilities	0	0
Derivative assets	0	4,325
Interest rate swaps and options | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	7,831,456	7,668,482
Derivative liabilities	60,204	65,131
Derivative assets	61,586	67,578
Notional amount of derivative assets	3,920,000	3,860,000
Notional amount of derivative liabilities	3,910,000	3,810,000
Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	1,270,000	767,800
Derivative liabilities	7,400	11,200
Derivative assets	8,200	11,900
RPAs | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	71,396	71,414
Derivative liabilities	2	3
Derivative assets	3	3
Interest rate derivative exposure	$ 112	$ 179
Weighted average remaining maturity (in years)	3 years 6 months	3 years 8 months
RPAs | Derivatives not designated as hedging instruments | Long
Derivative [Line Items]
Notional amount	$ 49,100	$ 48,300
RPAs | Derivatives not designated as hedging instruments | Short
Derivative [Line Items]
Notional amount	$ 22,300	$ 23,100