Stock Option Plan and Restricted Stock Plan - Schedule of Analysis of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding, beginning of year, Shares | shares	1,231,346
Granted, Shares | shares	0
Exercised, Shares | shares	(82,871)
Cancelled, Shares | shares	(54,440)
Outstanding, end of year, Shares | shares	1,094,035
Exercisable at end of year, Shares | shares	422,945
Outstanding, beginning of year, Weighted-Average Ex. Price | $ / shares	$ 26.70
Granted, Weighted-Average Ex. Price | $ / shares	0
Exercised, Weighted-Average Ex. Price | $ / shares	15.69
Cancelled, Weighted-Average Ex. Price | $ / shares	(29.52)
Outstanding, end of year, Weighted-Average Ex. Price | $ / shares	27.40
Exercisable at end of year, Weighted-Average Ex. Price | $ / shares	$ 20.38
Outstanding, end of year, Weighted-Average Remaining Contractual Term (Years)	6 years 6 months 22 days
Exercisable at end of year, Weighted-Average Remaining Contractual Term (Years)	4 years 3 months 15 days
Outstanding, end of year, Aggregate Intrinsic Value | $	$ 19,475
Exercisable at end of year, Aggregate Intrinsic Value | $	$ 10,498