Stock-Based Compensation - Summary of Activity Under Stock Incentive Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Outstanding, Beginning Balance	3,427,509
Shares Subject to Outstanding, Options granted	750,000
Shares Subject to Outstanding, Options exercised	(176,054)
Shares Subject to Outstanding, Options cancelled and forfeited	(233,162)
Shares Subject to Outstanding, Ending Balance	3,768,293
Shares Subject to Outstanding, Options vested and exercisable	2,848,655
Weighted-Average Exercise Price Per Share, Outstanding Beginning Balance	$ 3.76
Weighted-Average Exercise Price Per Share, Options granted	6.36
Weighted-Average Exercise Price Per Share, Options exercised	1.21
Weighted-Average Exercise Price Per Share, Options cancelled and forfeited	5.39
Weighted Average Exercise Price Per Share, Outstanding Ending Balance	4.30
Weighted Average Exercise Price Per Share, Options vested and exercisable	$ 3.58
Aggregate Intrinsic Value, Outstanding Balance	$ 2,500	$ 3,707
Aggregate Intrinsic Value, Options vested and exercisable	$ 2,252