Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 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	25,000
Options exercised | shares	(61,299)
Options canceled, forfeited or expired - Options | shares	(15,000)
Outstanding at ending period - Options | shares	966,850
Exercisable at ending period - Options | shares	476,175
Outstanding at beginning period - Wgtd. Avg. Exercise Price | $ / shares	$ 40.69
Options granted - Wgtd. Avg. Exercise Price | $ / shares	56.44
Options exercised - Wgtd. Avg. Exercise Price | $ / shares	30.61
Options cancelled, forfeited, or expired - Wgtd. Avg. Exercise Price | $ / shares	51.51
Outstanding at ending period - Wgtd. Avg. Exercise Price | $ / shares	41.57
Exercisable at ending period - Wgtd. Avg. Exercise Price | $ / shares	$ 33.92
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	8 years 9 months 4 days
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	5 years 7 months 13 days
Outstanding at ending period - Aggregate Intrinsic Value | $	$ 18,125
Exercisable at ending period - Aggregate Intrinsic Value | $	$ 12,571