Net Loss Per Share Attributable to Common Stockholders - Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	118,313,973	389,002,257	369,720,766
Company social impact initiatives period (in years)	8 years
Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares reserved for future issuance (in shares)	320,000
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	351,844,340	336,843,578
Warrants to purchase redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	203,610	203,610
Warrants to purchase Class B common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	1,900,000	1,419,528	3,669,528
Stock options outstanding, including early exercise of options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	45,307,479	23,421,374	25,159,411
Unvested RSUs outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	9,001,949	4,430,336	0
Shares committed under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	211,118	0	0
Stock options and RSUs available for future grants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	61,893,427	7,683,069	3,844,639