Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning period - Options | shares	707,450
Options exercised | shares	(76,450)
Outstanding at ending period - Options | shares	631,000
Exercisable at ending period - Options | shares	265,625
Outstanding at beginning period - Wgtd. Avg. Exercise Price | $ / shares	$ 44.92
Options exercised - Wgtd. Avg. Exercise Price | $ / shares	34.14
Outstanding at ending period - Wgtd. Avg. Exercise Price | $ / shares	46.23
Exercisable at ending period - Wgtd. Avg. Exercise Price | $ / shares	$ 38.46
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	9 years 9 months
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	6 years 10 months 17 days
Outstanding at ending period - Aggregate Intrinsic Value | $	$ 27,558
Exercisable at ending period - Aggregate Intrinsic Value | $	$ 13,663