Income Taxes - Reconciliation of IncomeTax Attributable to Pre-tax Income at Federal Statutory Tax Rates to Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax at statutory rate, value	$ 10,671	$ 11,336	$ 8,057
Tax exempt income, net value	(1,816)	(1,684)	(1,664)
Bank owned life insurance, value	(418)	(364)	(543)
Merger costs, value	30	0	233
Other, value	(175)	26	257
Income tax expense	$ 8,292	$ 9,314	$ 6,340
Tax at statutory rate, percent	35.00%	35.00%	35.00%
Tax exempt income, net percent	(6.00%)	(5.20%)	(7.20%)
Bank owned life insurance, percent	(1.40%)	(1.10%)	(2.40%)
Merger costs, percent	0.10%	0.00%	1.00%
Other, percent	(0.50%)	0.10%	1.10%
Income tax expense, percent	27.20%	28.80%	27.50%