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Common Stock - Reserved Common Stock for Future Issuances (Details) - shares | Sep. 30, 2021 | Dec. 31, 2020
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Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 11,434,564 | 29,782,878
Series A Redeemable Convertible Preferred Stock |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 7,608,688
Series B Redeemable Convertible Preferred Stock |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 2,419,242
Series C Redeemable Convertible Preferred Stock and Warrants |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 4,744,742
Series D Redeemable Convertible Preferred Stock |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 4,895,636
Series E Redeemable Convertible Preferred Stock |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 3,799,694
Series F Redeemable Convertible Preferred Stock and Warrants |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 0 | 2,725,430
Exercise of Options under Stock Plan |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 5,252,969 | 3,137,776
Issuance of options and restricted stock units under stock plan [Member] |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 5,331,595 | 451,670
Issuance of common stock under employee stock purchase plan |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Common stock reserved for future issuance | 850,000 | 0

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- Definition Aggregate number of common shares reserved for future issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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