Allowance for Credit Losses - Summary of Provision for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Provision for loan losses									$ 11,873	$ 7,846	$ 3,445
Provision for unfunded letters of credit									(4)	255	(1,561)
Total provision for credit losses	$ 3,800	$ 5,840	$ 1,429	$ 800	$ 3,507	$ 94	$ 4,500	$ 0	$ 11,869	$ 8,101	$ 1,884