Net Loss Per Share Attributable to Common Stockholders -Schedule of Antidilutive Shares (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	0	54,041,904	0	54,041,904
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	5,713,130	8,142,132	5,713,130	8,142,132
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	3,354,991	1,465,044	3,354,991	1,465,044
Unvested performance stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	4,397,688	0	4,397,688	0
Warrants to purchase Series B redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	0	21,745	0	21,745