Stockholders' Equity - Summary of Stock Option Activity Under the 2010 Stock Plan and the 2013 Stock Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Outstanding, beginning balance	2,792,021
Number of Shares, Granted	164,742
Number of Shares, Exercised	(1,010,085)
Number of Shares, Cancelled	(121,045)
Number of Shares, Outstanding, ending balance	1,825,633	2,792,021
Number of Shares, Exercisable as of September 30, 2015	737,282
Weighted-Average Exercise Price, Outstanding, beginning balance	$ 10.82
Weighted-Average Exercise Price, Granted	45.09
Weighted-Average Exercise Price, Exercised	4.41
Weighted-Average Exercise Price, Cancelled	17.12
Weighted- Average Exercise Price, Outstanding, ending balance	17.04	$ 10.82
Weighted- Average Exercise Price, Exercisable as of September 30, 2015	$ 11.74
Weighted-Average Remaining Contractual Term, Outstanding, beginning balance	8 years	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Exercisable as of September 30, 2015	7 years 6 months
Aggregate Intrinsic Value, Outstanding, beginning balance	$ 35,390
Aggregate Intrinsic Value, Outstanding, ending balance	12,686	$ 35,390
Aggregate Intrinsic Value, Exercisable as of September 30, 2015	$ 6,986