Employee retirement plans - Schedule of Defined Contribution Expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Retirement Benefits [Abstract] | ||||
| Defined contribution expense | $ 255 | $ 220 | $ 733 | $ 629 |