Stockholders' Equity - Summary of Stock Option Activity Under the 2010 Stock Plan and the 2013 Stock Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding, beginning balance	1,267,329
Number of Shares, Granted	0
Number of Shares, Exercised	(549,280)
Number of Shares, Forfeited	(51,332)
Number of Shares, Outstanding, ending balance	666,717	1,267,329
Number of Shares, Exercisable as of December 31, 2017	595,665
Number of Shares, Vested and expected to vest at December 31, 2017	666,717
Weighted-Average Exercise Price, Outstanding, beginning balance	$ 16.22
Weighted-Average Exercise Price, Exercised	11.45
Weighted-Average Exercise Price, Exercised, Forfeited	24.39
Weighted-Average Exercise Price, Outstanding, ending balance	19.53	$ 16.22
Weighted-Average Exercise Price, Exercisable as of December 31, 2017	18.37
Weighted-Average Exercise Price, Vested and expected to vest at December 31, 2017	$ 19.53
Weighted-Average Remaining Contractual Term, Outstanding	5 years 7 months 6 days	6 years 7 months 6 days
Weighted-Average Remaining Contractual Term, Exercisable as of December 31, 2017	5 years 6 months
Weighted-Average Remaining Contractual Term, Vested and expected to vest at December 31, 2017	5 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding	$ 32,450	$ 8,355
Aggregate Intrinsic Value, Exercisable as of December 31, 2017	29,684
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2017	$ 32,450