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
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net loss	$ (29,722)	$ (24,231)
Weighted-average shares used to compute basic and diluted net loss per share	35,004	29,422
Basic and diluted net loss per common share	$ (0.85)	$ (0.82)