Derivatives (Details 2) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) company	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Derivative liabilities	$ 90,915	$ 82,323
Derivative assets	80,466	83,780
Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	42,566	131,391
Derivative liabilities	6,648	5,976
Derivative assets	0	4,325
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	9,942,781	8,507,660
Derivative liabilities	84,267	76,347
Derivative assets	80,466	79,455
Interest rate swaps on certificates of deposit | Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	42,566	48,365
Derivative liabilities	6,648	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	8,742,980	7,668,482
Derivative liabilities	64,212	65,131
Derivative assets	64,822	67,578
Notional amount of derivative assets	4,370,000	3,860,000
Notional amount of derivative liabilities	4,370,000	3,810,000
Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	1,131,414	767,764
Derivative liabilities	20,054	11,213
Derivative assets	14,187	11,874
RPAs | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	68,387	71,414
Derivative liabilities	1	3
Derivative assets	$ 2	$ 3
Weighted average remaining maturity (in years)	3 years	3 years 8 months
RPAs | Derivatives not designated as hedging instruments | Long
Derivative [Line Items]
Notional amount	$ 47,800	$ 48,300
Derivative liabilities	1	3
Interest rate derivative exposure	92	179
RPAs | Derivatives not designated as hedging instruments | Short
Derivative [Line Items]
Notional amount	20,600	23,100
Derivative assets	2	3
Warrants | Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	0	0
Derivative liabilities	0	0
Derivative assets	1,455	$ 0
Warrant, Public Companies | Derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative assets	$ 856
Number of companies in which warrants are held | company	4
Warrant, Private Companies | Derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative assets	$ 599
Number of companies in which warrants are held | company	32