Other Noninterest Income and Other Noninterest Expense - Summary of Other Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Income and Expenses [Abstract]
Lending and other client related processing costs	$ 6,935	$ 5,885	$ 18,806	$ 13,721
Telephone	2,518	2,460	7,892	7,109
Data processing services	2,244	2,137	7,254	6,353
Dues and publications	883	809	2,355	2,258
Postage and supplies	612	598	2,013	2,172
Other	4,872	3,644	16,350	12,679
Total other noninterest expense	$ 18,064	$ 15,533	$ 54,670	$ 44,292