Share-Based Compensation - Share-Based Payment Award Activity (Detail)	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Options
Outstanding, beginning of period, in shares | shares	1,137,228
Granted, in shares | shares	175,433
Exercised, in shares | shares	(108,199)
Forfeited, in shares | shares	(11,043)
Expired, in shares | shares	(190)
Outstanding, end of period, in shares | shares	1,193,229
Vested and expected to vest, end of period, in shares | shares	1,157,616
Exercisable, end of period, in shares | shares	737,697
Weighted Average Exercise Price
Outstanding, beginning of period, in usd per share | $ / shares	$ 77.12
Granted, in usd per share | $ / shares	105.18
Exercised, in usd per share | $ / shares	39.48
Forfeited, in usd per share | $ / shares	94.88
Expired, in usd per share | $ / shares	19.48
Outstanding, end of period, in usd per share | $ / shares	84.51
Vested and expected to vest, end of period, in usd per share | $ / shares	83.78
Exercisable, end of period, in usd per share | $ / shares	$ 71.64
Weighted Average Remaining Contractual Life - in Years
Outstanding, end of period	4 years 11 days
Vested and expected to vest, end of period	3 years 11 months 19 days
Exercisable, end of period	3 years 7 days
Aggregate Intrinsic Value of In-The-Money Options
Outstanding, end of period | $	$ 21,461,860
Vested and expected to vest, end of period | $	21,397,505
Exercisable, end of period | $	$ 19,756,003