Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning period - Options | shares	1,018,149
Options granted | shares	30,000
Options exercised | shares	(195,174)
Options canceled, forfeited or expired - Options | shares	(30,000)
Outstanding at ending period - Options | shares	822,975
Exercisable at ending period - Options | shares	370,350
Outstanding at beginning period - Wgtd. Avg. Exercise Price | $ / shares	$ 40.69
Options granted - Wgtd. Avg. Exercise Price | $ / shares	58.08
Options exercised - Wgtd. Avg. Exercise Price | $ / shares	29.38
Options cancelled, forfeited, or expired - Wgtd. Avg. Exercise Price | $ / shares	55.88
Outstanding at ending period - Wgtd. Avg. Exercise Price | $ / shares	43.46
Exercisable at ending period - Wgtd. Avg. Exercise Price | $ / shares	$ 36.00
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	9 years 4 months 6 days
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	6 years 5 months 12 days
Outstanding at ending period - Aggregate Intrinsic Value | $	$ 23,910
Exercisable at ending period - Aggregate Intrinsic Value | $	$ 13,521