Other Noninterest Income and Expense - Summary of Other Noninterest Income and Other Noninterest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income and Expenses [Abstract]
Gain on branch sales	$ 14,717	$ 0	$ 14,717	$ 0
Loan servicing rights impairment	(8,858)	0	(17,094)	0
Other	8,266	5,373	30,085	11,997
Total other noninterest income	14,125	5,373	27,708	11,997
Outside processing	12,804	5,917	26,717	11,391
Loan and lease expense	8,356	3,374	16,139	6,663
Professional fees	5,628	5,385	12,197	10,913
Advertising and marketing	4,463	5,273	12,840	12,128
FDIC insurance	6,742	2,492	13,301	5,410
Card processing and issuance costs	5,831	4,183	14,521	8,691
Other	29,682	26,302	66,537	51,809
Total other noninterest expense	$ 73,506	$ 52,926	$ 162,252	$ 107,005