Net Loss per Share - Schedule of antidilutive securities excluded from computation of earnings per share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	22,205,406	84,496,929
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	0	68,776,612
Outstanding stock options - Stock Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	2,852,530	6,149,668
Warrant | Warrants for preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	0	9,570,649
Warrant | Warrants for common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	7,846,646	0
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive securities (in shares)	11,506,230	0