Stock-Based Compensation - Components of Stock-Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Total stock-based compensation expense	$ 1,809	$ 2,322	$ 1,798
Tax benefit of stock-based compensation expense	(696)	(892)	(671)
After-tax effect of stock based compensation	1,113	1,430	1,127
Stock options
Total stock-based compensation expense	194	236	(245)
Restricted stock units
Total stock-based compensation expense	1,615	2,086	2,043
Deferred directors fees
Total stock-based compensation expense	$ 0	$ 0	$ 0