Investments and fair value measurements - Summary of Mortgage Loans (Details) - USD ($) $ in Thousands |
Mar. 31, 2022 |
Dec. 31, 2021 |
|---|---|---|
| Net Investment Income [Line Items] | ||
| Mortgage loans | $ 1,141 | $ 2,022 |
| Cost | ||
| Net Investment Income [Line Items] | ||
| Mortgage loans | 1,141 | 2,022 |
| Estimated Fair Value | ||
| Net Investment Income [Line Items] | ||
| Mortgage loans | $ 1,141 | $ 2,022 |