Derivative Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative instruments, gain (loss)
Notional Amount
Derivatives not designated as hedges
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	26,533	$ (5,094)
Notional Amount
Derivatives not designated as hedges | Interest rate contracts
Derivative instruments, gain (loss)
Notional Amount	5,875,131		5,095,969
Derivatives not designated as hedges | Interest rate contracts | Other noninterest income
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	1,662	(487)
Derivatives not designated as hedges | Risk participation agreements
Derivative instruments, gain (loss)
Notional Amount	398,579		316,353
Derivatives not designated as hedges | Risk participation agreements | Other noninterest expense
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	4,326	(321)
Derivatives not designated as hedges | Forward foreign exchange contracts
Derivative instruments, gain (loss)
Notional Amount	239,076		262,656
Derivatives not designated as hedges | Forward foreign exchange contracts | Other noninterest expense
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	18,713	(4,779)
Derivatives not designated as hedges | Interest rate lock commitments
Derivative instruments, gain (loss)
Notional Amount	452,544		158,111
Derivatives not designated as hedges | Interest rate lock commitments | Net gains on sales of loans and leases
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	10,378	493
Derivatives not designated as hedges | Forward loan sales commitments
Derivative instruments, gain (loss)
Notional Amount	539,741		174,013
Derivatives not designated as hedges | Forward loan sales commitments | Net gains on sales of loans and leases
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	(8,545)	0
Derivatives not designated as hedges | Swap agreement
Derivative instruments, gain (loss)
Notional Amount	12,652		$ 12,652
Derivatives not designated as hedges | Swap agreement | Other noninterest income
Derivative instruments, gain (loss)
Net gain (loss) of derivatives included in the Consolidated Statements of Income	$ (1)	$ 0