Other Noninterest Expense - Summary of Other Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Lending and other client related processing costs	$ 7,403	$ 6,332	$ 10,603	$ 11,871
Data processing services	2,703	2,428	5,195	5,010
Telephone	2,378	2,671	4,756	5,374
Dues and publications	845	677	1,694	1,472
Postage and supplies	813	652	1,480	1,401
Other	4,670	7,639	9,778	11,478
Total other noninterest expense	$ 18,812	$ 20,399	$ 33,506	$ 36,606