Provision for Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Expected tax expense, at the U.S. federal statutory income tax rate of 35%			$ 4,096	$ 4,016
Domestic production activities deduction			(362)	(369)
State income taxes			339	342
Other, net			24	19
Total income tax expense	$ 1,592	$ 1,209	$ 4,097	$ 4,008