Employee future benefits - Net Defined Benefit Liability (Asset) (Details) - USD ($) $ in Thousands |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|---|
| Disclosure of net defined benefit liability (asset) [line items] | |||
| Employee future benefits | $ 455 | $ 1,894 | |
| Net defined benefit pension plan liability | |||
| Disclosure of net defined benefit liability (asset) [line items] | |||
| Employee future benefits | 348 | 1,814 | $ 3,856 |
| Net other post-retirement benefit plan liability | |||
| Disclosure of net defined benefit liability (asset) [line items] | |||
| Employee future benefits | $ 107 | $ 80 | $ 85 |