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Redeemable Convertible Preferred Stock and Stockholders’ Equity - Common Stock Reserved for Future Issuance (Details) - shares | Sep. 30, 2021 | Dec. 31, 2020
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Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) | 20,116,805 | 39,401,631
Employee Stock |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) | 12,730,521 | 1,938,321
Options outstanding |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) | 7,064,945 | 7,611,258
Restricted stock outstanding |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) | 156,852 | 156,852
Conversion of Series A Preferred Stock |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) |  | 10,138,200
Conversion of Series A-1 Preferred Stock |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) |  | 5,512,800
Conversion of Series B Preferred Stock |  |
Class of Stock [Line Items] |  |
Total authorized shares of common stock reserved for future issuance (in shares) |  | 14,044,200

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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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