Net Loss Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (22,903)	$ (26,119)	$ (81,787)	$ (73,293)
Denominator:
Weighted-average shares outstanding - basic and diluted	147,877	141,034	146,270	138,907
Net loss per common share - basic and diluted:	$ (0.15)	$ (0.19)	$ (0.56)	$ (0.53)