Stock Plans - Stock-based compensation expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2020 |
|
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||||
| Total stock-based compensation expense | $ 447 | $ 79 | $ 695 | $ (5) |
| Research and development | ||||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||||
| Total stock-based compensation expense | 214 | 0 | 334 | 0 |
| Selling, general and administrative | ||||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost | ||||
| Total stock-based compensation expense | $ 233 | $ 79 | $ 361 | $ (5) |