Income Taxes - Valuation allowance for deferred tax assets (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
|
| Deferred Tax Asset, Valuation Allowance Activity [Roll Forward] | |||
| Valuation allowance as of beginning of year | $ 206,707 | $ 139,877 | $ 85,884 |
| Decreases recorded as benefit to income tax provision | 0 | 0 | 0 |
| Increases recorded to income tax provision | 56,722 | 66,830 | 53,993 |
| Valuation allowance as of end of year | $ 263,429 | $ 206,707 | $ 139,877 |