Nature of the Business and Basis of Presentation (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Mar. 18, 2021 |
Jul. 20, 2018 |
Sep. 30, 2021 |
Jun. 30, 2021 |
Mar. 31, 2021 |
Sep. 30, 2020 |
Jun. 30, 2020 |
Mar. 31, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
|
| Sale of Equity | |||||||||||
| Net proceeds after deducting underwriting discounts and commissions | $ 188,000 | ||||||||||
| Net Loss | $ (49,016) | $ (50,180) | $ (42,330) | $ (40,852) | $ (37,854) | $ (48,486) | (141,526) | $ (127,192) | $ (167,700) | ||
| Accumulated deficit | $ (621,997) | $ (621,997) | $ (480,471) | ||||||||
| Common stock | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 6,896,552 | ||||||||||
| Conversion of redeemable convertible preferred stock to common stock (in shares) | 51,845,438 | ||||||||||
| IPO | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 12,055,450 | ||||||||||
| Net proceeds after deducting underwriting discounts and commissions | $ 254,300 | ||||||||||
| Offering | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 6,896,552 | ||||||||||
| Net proceeds after deducting underwriting discounts and commissions | $ 187,200 | ||||||||||
| Overallotment | |||||||||||
| Sale of Equity | |||||||||||
| Shares issued (in shares) | 1,572,450 | ||||||||||