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, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net loss	$ (24,231)	$ (22,006)
Weighted-average shares used to compute basic and diluted net loss per share	29,422	27,810
Basic and diluted net loss per common share	$ (0.82)	$ (0.79)