Allowance for Credit Losses - Summary of Provision for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Receivables [Abstract]
Provision for loans	$ 5,949	$ 0	$ 8,041	$ 4,382
Provision for unfunded letters of credit	(109)	94	28	212
Total provision for credit losses	$ 5,840	$ 94	$ 8,069	$ 4,594