Net Loss per Share of Common Stock - Summary of Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net loss	$ (22,118)	$ (19,667)	$ (46,349)	$ (41,673)
Weighted-average shares used to compute basic and diluted net loss per share	29,489	29,293	29,455	26,035
Basic and diluted net loss per common share	$ (0.75)	$ (0.67)	$ (1.57)	$ (1.60)