Net Loss per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Basic and diluted loss per share:
Net loss	$ (8,685)	$ (10,004)
Weighted-average common shares outstanding	50,803	6,916
Less: weighted-average unvested common shares subject to repurchase	(364)	(1,627)
Weighted-average number of shares used in computing net loss per share, basic and diluted	50,439	5,289
Basic and diluted net loss per share (in dollars per share)	$ (0.17)	$ (1.89)