Summary of Option Activity (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Options Outstanding
Options outstanding at December 31, 2017 | shares	734,940
Granted | shares	398,532
Exercised | shares	(14,531)
Forfeited/cancelled | shares	(9,588)
Options outstanding at March 31, 2018 | shares	1,109,353
Options exercisable at March 31, 2018 | shares	499,504
Vested and expected to vest at March 31, 2018 | shares	1,057,255	[1]
Weighted-Average Exercise Price Per Share
Options outstanding at December 31, 2017 | $ / shares	$ 20.80
Granted | $ / shares	33.85
Exercised | $ / shares	23.70
Forfeited/cancelled | $ / shares	29.71
Options outstanding at March 31, 2018 | $ / shares	25.34
Options exercisable at March 31, 2018 | $ / shares	17.73
Vested and expected to vest at March 31, 2018 | $ / shares	$ 24.96	[1]
Weighted-Average Remaining Contractual Term (in years)
Options outstanding at March 31, 2018	7 years 6 months 3 days
Options exercisable at March 31, 2018	5 years 6 months
Vested and expected to vest at March 31, 2018	7 years 4 months 24 days	[1]
Aggregate Intrinsic Value
Options outstanding at March 31, 2018 | $	$ 12,176
Options exercisable at March 31, 2018 | $	9,300
Vested and expected to vest at March 31, 2018 | $	$ 12,015	[1]

[1] Represents the number of vested options as of March 31, 2018 plus the number of unvested options expected to vest as of March 31, 2018 based on the unvested outstanding options at March 31, 2018 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.