Allowance for Loan Losses - Summary of Changes in Allowance for Loan 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]
Allowance for loan losses, beginning of period	$ 23,863	$ 22,245	$ 23,075	$ 22,318
Loans charged off	(118)	(129)	(298)	(613)
Recoveries on loans previously charged-off	93	214	345	425
Net recoveries (charge-offs)	(25)	85	47	(188)
Provision charged to expense	375		1,175	200
Reclassification to other liabilities	(5)		(89)
Allowance for loan losses, end of period	$ 24,208	$ 22,330	$ 24,208	$ 22,330