Net Loss Per Share - Computation of Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (43,587)	$ (18,108)	$ (121,931)	$ (65,437)
Denominator:
Weighted average common shares outstanding - basic	104,144,606	89,365,798	100,480,156	89,109,772
Weighted average common shares outstanding - diluted	104,144,606	89,365,798	100,480,156	89,109,772
Net loss per share - basic (in dollars per share)	$ (0.42)	$ (0.20)	$ (1.21)	$ (0.73)
Net loss per share - diluted (in dollars per share)	$ (0.42)	$ (0.20)	$ (1.21)	$ (0.73)