Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net loss	$ (5,858)	$ (17,640)	$ (40,795)	$ (60,708)
Weighted-average shares used to compute net loss per share (in shares)	101,736	96,709	100,272	95,433
Net loss per share, basic and diluted (in usd per share)	$ (0.06)	$ (0.18)	$ (0.41)	$ (0.64)