Stock-Based Compensation - Schedule of Stock Options Activity (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
NUMBER OF SHARES
Beginning balance (in shares) | shares	6,935,119
Granted (in shares) | shares	753,010
Exercised (in shares) | shares	(111,242)
Canceled (in shares) | shares	(132,151)
Ending balance (in shares) | shares	7,444,736
Options exercisable (in shares) | shares	4,908,673
WEIGHTED AVERAGE EXERCISE PRICE
Beginning balance (in dollars per share) | $ / shares	$ 28.97
Granted (in dollars per share) | $ / shares	43.94
Exercised (in dollars per share) | $ / shares	32.96
Canceled (in dollars per share) | $ / shares	52.08
Ending balance (in dollars per share) | $ / shares	30.01
Options exercisable (in dollars per share) | $ / shares	$ 20.97
WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE (YEARS)
Options outstanding, weighted average remaining contractual life	6 years 9 months 5 days
Options exercisable	5 years 8 months 5 days
AGGREGATE INTRINSIC VALUE
Options outstanding | $	$ 145,052
Options exercisable | $	$ 134,432