Stock Options and Restricted Stock - Weighted Average Grant Date Fair Values of Options Granted (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cash received from option exercises	$ 1,844	$ 2,674	$ 2,344
Total tax benefits realized for tax deductions from options exercised	2,109	2,797	2,002
Total intrinsic value of options exercised	6,969	9,145	6,654
Grant date fair value of options vested		144	226
Aggregate intrinsic value of vested options outstanding	$ 3,448	$ 8,763	$ 17,467