Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (68,760)	$ (64,078)	$ (38,547)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	81,979	37,540	19,500
Net loss per share, basic and diluted (in dollars per share)	$ (0.84)	$ (1.71)	$ (1.98)