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Derivative Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	$ 1,863	$ 5,988
Terminated interest rate swaps	177,810		$ 263,349
Interest rate contracts
Derivative instruments, gain (loss)
Terminated interest rate swaps	164,438		248,267
Risk participation agreements
Derivative instruments, gain (loss)
Terminated interest rate swaps	27		62
Forward foreign exchange contracts
Derivative instruments, gain (loss)
Terminated interest rate swaps	623		0
Interest rate lock commitments
Derivative instruments, gain (loss)
Terminated interest rate swaps	6,907		14,561
Forward loan sales commitments
Derivative instruments, gain (loss)
Terminated interest rate swaps	5,515		$ 0
Derivatives not designated as hedges
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	3,284	26,533
Derivatives not designated as hedges \| Interest Rate Swap [Member]
Derivative instruments, gain (loss)
Loss on termination of interest rate swaps		17,300
Derivatives not designated as hedges \| Interest rate contracts \| Other noninterest income
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	255	1,662
Derivatives not designated as hedges \| Risk participation agreements \| Other noninterest expense
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	1,607	4,326
Derivatives not designated as hedges \| Forward foreign exchange contracts \| Other noninterest expense
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	10	18,713
Derivatives not designated as hedges \| Interest rate lock commitments \| Mortgage banking income
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	(7,189)	10,378
Derivatives not designated as hedges \| Forward loan sales commitments \| Mortgage banking income
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	8,889	(8,545)
Derivatives not designated as hedges \| Swap agreement \| Other noninterest income
Derivative instruments, gain (loss)
Interest rate swap mark-to-market adjustment	$ (288)	$ (1)