Net Loss per Share - Schedule of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net loss	$ (9,818)	$ (782)	$ (23,161)	$ (21,721)
Weighted-average number of common shares used in computing net loss per share attributable to common stockholders, basic and diluted	82,831	78,065	83,335	63,542
Net loss per share attributable to common stockholders, basic and diluted	$ (0.12)	$ (0.01)	$ (0.28)	$ (0.34)