Stock-Based Compensation - Stock-Based Employee Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Labor And Related Expense [Abstract]
Stock-based compensation expense	$ 1,636	$ 1,717	$ 1,676
Tax benefit	633	664	648
Stock-based compensation expense, net of tax	$ 1,003	$ 1,053	$ 1,028