Derivatives (Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments) (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	$ 2,137	$ 5,771	$ 10,016	$ 13,878
Interest rate contracts | Interest rate contracts and other derivative income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	(2,738)	653	(5,876)	1,847
Foreign exchange contracts | Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	5,306	4,612	15,127	11,115
Credit contracts | Interest rate contracts and other derivative income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	(3)	20	44	(49)
Equity contracts | Lending fees
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	(442)	531	725	970
Commodity contracts | Interest rate contracts and other derivative income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	$ 14	$ (45)	$ (4)	$ (5)