Long-term investments - Additional Informational (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Long-term investments | $ 53,925,000 | $ 0 | $ 0 |
| Impairment Losses, Investments | 626,000 | $ 0 | $ 0 |
| Equity investees net loss or income | 300 | ||
| Unrealized gains and interest recorded, convertible bonds | 200,000 | ||
| Equity Securities, FV-NI, Cost | 36,500,000 | ||
| Proceeds from equity method investment distributions | $ 500,000 | ||