Net Loss Per Share - Computation (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 attributable to common stockholders, basic	$ (26,615)	$ (9,104)	$ (66,421)	$ (18,667)
Net loss attributable to common stockholders, diluted	$ (26,615)	$ (9,104)	$ (66,421)	$ (18,667)
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average shares outstanding, basic	172,987,672	87,398,704	171,842,664	86,981,200
Weighted average shares outstanding, diluted	172,987,672	87,398,704	171,842,664	86,981,200
Net loss per share, basic (usd per share)	$ (0.15)	$ (0.10)	$ (0.39)	$ (0.21)
Net loss per share, diluted (usd per share)	$ (0.15)	$ (0.10)	$ (0.39)	$ (0.21)
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unexercised incentive and non-qualified stock options (in shares)			3,551,320	7,051,237
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unexercised incentive and non-qualified stock options (in shares)			3,604,614	0