Basic and Diluted Net Loss Per Share - Computation of Company's Basic and Diluted Net Loss Per Share of Common Stock (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator
Net loss	$ (6,613)	$ (10,611)
Denominator
Weighted-average common shares for basic and diluted net loss per share	72,114	68,764
Basic and diluted net loss per share	$ (0.09)	$ (0.15)