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Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Jun. 30, 2021 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020 | Jun. 30, 2020 | Dec. 31, 2019
Description Of Organization [Line Items] |  |  |  |  |  |
Proceeds from initial public offering, net of underwriters' discounts and commissions |  | $ 391,802 |  |  |  |
Outstanding convertible preferred stock (in shares) |  | 0 |  | 194,474,000 |  |
Convertible Preferred Stock |  |  |  |  |  |
Description Of Organization [Line Items] |  |  |  |  |  |
Conversion of preferred stock into common stock (in shares) |  | 194,474,000 |  |  |  |
Outstanding convertible preferred stock (in shares) |  |  | 194,474,000 | 194,474,000 | 194,474,000 | 152,116,000
Common Stock |  |  |  |  |  |
Description Of Organization [Line Items] |  |  |  |  |  |
Conversion of preferred stock into common stock (in shares) |  | 194,474,000 |  |  |  |
IPO | Convertible Preferred Stock |  |  |  |  |  |
Description Of Organization [Line Items] |  |  |  |  |  |
Conversion of preferred stock into common stock (in shares) | 194,474,431 |  |  |  |  |
IPO | Common Stock |  |  |  |  |  |
Description Of Organization [Line Items] |  |  |  |  |  |
Issuance of common stock, shares | 25,000,000 |  |  |  |  |
Payments of underwriting discounts and commissions | $ 29,800 |  |  |  |  |
Proceeds from initial public offering, net of underwriters' discounts and commissions | $ 391,800 |  |  |  |  |
Common stock price per share | $ 17.00 |  |  |  |  |
Offering expenses | $ 3,400 |  |  |  |  |
IPO | Common Stock Including Additional Paid in Capital |  |  |  |  |  |
Description Of Organization [Line Items] |  |  |  |  |  |
Converted preferred stock | $ 1,000,000 |  |  |  |  |

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