Other Noninterest Income and Other Noninterest Expense - Summary of Other Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Income and Expenses [Abstract]
Lending and other client related processing costs	$ 6,332	$ 3,541	$ 11,871	$ 7,836
Telephone	2,671	2,416	5,374	4,649
Data processing services	2,428	2,387	5,010	4,216
Dues and publications	677	647	1,472	1,449
Postage and supplies	652	784	1,401	1,574
Other	7,639	4,191	11,478	9,035
Total other noninterest expense	$ 20,399	$ 13,966	$ 36,606	$ 28,759