Derivatives (Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments) (Details) - Derivative instruments not designated as hedging instruments - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	$ 17,409	$ 21,969	$ 15,189
Interest rate contracts | Derivative fees and other income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	280	(1,772)	2,557
Foreign exchange contracts | Letters of credit fees and foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	16,784	22,076	12,632
Credit contracts | Derivative fees and other income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	(156)	(7)	0
Equity contracts | Ancillary loan fees and other income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	512	1,672	0
Commodity contracts | Derivative fees and other income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recognized for derivative not designated as hedging instruments	$ (11)	$ 0	$ 0