Share-Based Compensation - Share-Based Payment Award Activity (Detail)	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Options
Outstanding, beginning of period, in shares | shares	1,137,228.000
Granted, in shares | shares	177,203
Exercised, in shares | shares	(141,248)
Forfeited, in shares | shares	(19,305)
Expired, in shares | shares	(190)
Outstanding, end of period, in shares | shares	1,153,688
Vested and expected to vest, end of period, in shares | shares	1,123,538
Exercisable, end of period, in shares | shares	706,677
Weighted Average Exercise Price
Outstanding, beginning of period, in usd per share | $ / shares	$ 77.12
Granted, in usd per share | $ / shares	105.11
Exercised, in usd per share | $ / shares	43.90
Forfeited, in usd per share | $ / shares	100.80
Expired, in usd per share | $ / shares	19.48
Outstanding, end of period, in usd per share | $ / shares	85.10
Vested and expected to vest, end of period, in usd per share | $ / shares	84.47
Exercisable, end of period, in usd per share | $ / shares	$ 72.25
Weighted Average Remaining Contractual Life - in Years
Outstanding, end of period	3 years 9 months 29 days
Vested and expected to vest, end of period	3 years 9 months 7 days
Exercisable, end of period	2 years 9 months 22 days
Aggregate Intrinsic Value of In-The-Money Options
Outstanding, end of period | $	$ 31,649,669
Vested and expected to vest, end of period | $	31,469,498
Exercisable, end of period | $	$ 27,648,800