Other Noninterest Expense - Summary of Other Noninterest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Income and Expenses [Abstract]
Lending and other client related processing costs	$ 8,763	$ 7,403	$ 13,940	$ 10,603
Correspondent bank fees	3,569	3,277	7,313	6,687
Investment banking activities	3,869	0	8,054	0
Trade order execution costs	2,828	0	5,344	0
Data processing services	2,659	2,703	5,558	5,195
Telephone	2,422	2,378	5,163	4,756
Dues and publications	860	845	2,384	1,694
Postage and supplies	678	813	1,448	1,480
Other	11,769	4,670	21,749	9,778
Total other noninterest expense	$ 37,417	$ 22,089	$ 70,953	$ 40,193