Other Noninterest Income and Expense - Summary of Other Noninterest Income and Other Noninterest Expense (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Other Income and Expenses [Abstract]
Gain on branch sales	$ 0	$ 0	$ 14,717	$ 0
Termination of interest rate swaps	0	(17,302)	0	(17,302)
Loan servicing rights impairment	(154)	(4,520)	(17,248)	(4,520)
Other	5,565	9,513	35,650	21,510
Total other noninterest income	5,411	(12,309)	33,119	(312)
Outside processing	15,697	12,084	42,414	23,475
Loan and lease expense	7,849	6,750	23,988	13,413
Professional fees	6,552	7,406	18,749	18,319
Advertising and marketing	8,251	7,101	21,091	19,229
FDIC insurance	5,138	6,298	18,439	11,708
Card processing and issuance costs	6,064	5,746	20,585	14,437
Other	33,872	42,391	100,409	94,200
Total other noninterest expense	$ 83,423	$ 87,776	$ 245,675	$ 194,781
Number of branch sales	7		7