Stock Plans - Schedule of Stock Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Restricted stock	$ 3,456	$ 3,035	$ 4,026
Stock options	2,459	2,454	2,355
Performance stock	3,296	2,110	2,672
Total compensation expense before income taxes	9,211	7,599	9,053
Income tax benefit	3,375	2,896	3,293
Total compensation expense, net of income tax benefit	$ 5,836	$ 4,703	$ 5,760