Stockholders' Equity - Summary of Stock Option Activity Under the 2010 Stock Plan and the 2013 Stock Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding, beginning balance	666,717
Number of Shares, Exercised	(184,783)
Number of Shares, Forfeited	(3,802)
Number of Shares, Outstanding, ending balance	478,132	666,717
Number of Shares, Exercisable as of March 31, 2018	440,089
Weighted-Average Exercise Price, Outstanding, beginning balance	$ 19.53
Weighted-Average Exercise Price, Exercised	18.56
Weighted-Average Exercise Price, Exercised, Forfeited	25.40
Weighted- Average Exercise Price, Outstanding, ending balance	19.86	$ 19.53
Weighted-Average Exercise Price, Exercisable as of March 31, 2018	$ 18.74
Weighted-Average Remaining Contractual Term, Outstanding	5 years 3 months 18 days	5 years 7 months 6 days
Weighted-Average Remaining Contractual Term, Exercisable as of March 31, 2018	5 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding	$ 28,159	$ 32,450
Aggregate Intrinsic Value, Exercisable as of March 31, 2018	$ 26,409