Equity Awards - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
Number of Shares
Outstanding, beginning balance (in shares) | shares	1,810,580
Exercised (in shares) | shares	(231,558)
Outstanding, ending balance (in shares) | shares	1,579,022
Vested and expected to vest (in shares) | shares	1,574,667
Vested and exercisable (in shares) | shares	1,147,276
Weighted- Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 46.55
Exercised (in dollars per share) | $ / shares	21.69
Outstanding, ending balance (in dollars per share) | $ / shares	50.19
Vested and expected to vest (in dollars per share) | $ / shares	50.13
Vested and exercisable (in dollars per share) | $ / shares	$ 37.62
Weighted-average remaining contractual term, outstanding	5 years 2 months 26 days
Weighted-average remaining contractual term, vested and expected to vest	5 years 2 months 23 days
Weighted-average remaining contractual term, vested and exercisable	4 years 3 months 14 days
Aggregate intrinsic value, exercised | $	$ 46,348
Aggregate intrinsic value, outstanding | $	309,955
Aggregate intrinsic value, vested and expected to vest | $	309,205
Aggregate intrinsic value, vested and exercisable | $	$ 239,629