Income Taxes - Summary of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Current - federal	$ 7,777	$ 8,471	$ 7,189
Current - state	139	110	128
Deferred - federal	376	733	(977)
Income tax expense	$ 8,292	$ 9,314	$ 6,340