Retirement benefit plan - Summary of Benefit Plan (Details) - CHF (SFr) SFr in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Retirement benefit plan | |||
| Percentage of contribution by employees | 47.00% | ||
| Percentage of contribution by employer | 53.00% | ||
| Defined benefit pension plan amount recognized in balance sheet [Abstract] | |||
| Defined benefit obligation | SFr (48,261) | SFr (52,455) | SFr (41,060) |
| Fair value of plan assets | 39,615 | 43,611 | 35,290 |
| Total liability | SFr (8,646) | SFr (8,844) | SFr (5,770) |