Other Noninterest Expense - Summary of Other Noninterest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Income and Expenses [Abstract]
Lending and other client related processing costs	$ 7,502	$ 5,698	$ 21,442	$ 16,301
Correspondent bank fees	3,657	3,513	10,970	10,200
Investment banking activities	1,864	0	9,918	0
Trade order execution costs	2,615	0	7,959	0
Data processing services	3,066	2,740	8,624	7,934
Telephone	2,466	2,269	7,629	7,025
Dues and publications	1,055	1,387	3,439	3,081
Postage and supplies	720	652	2,168	2,133
Other	11,161	5,393	32,910	15,171
Total other noninterest expense	$ 34,106	$ 21,652	$ 105,059	$ 61,845