Basis of preparation and changes to the Company's accounting policies - Functional and reporting currency (Details) - SFr / $ |
3 Months Ended | 6 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
Dec. 31, 2024 |
|
| Foreign exchange rates [abstract] | |||||
| Closing foreign exchange rate | 0.807 | 0.909 | 0.807 | 0.909 | 0.912 |
| Average foreign exchange rate | 0.837 | 0.914 | 0.873 | 0.898 | 0.889 |