Net Loss per Share - Computation of Basic and Diluted Net Loss per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net loss	$ (27,171)	$ (19,168)
Basic shares:
Weighted-average shares used to compute basic net loss per share	90,519	76,338
Diluted shares:
Weighted-average shares used to compute diluted net loss per share	90,519	76,338
Net loss per share:
Basic and diluted	$ (0.30)	$ (0.25)