Income taxes - Tax years (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2025 | |
| Switzerland | |
| Income taxes | |
| Tax years remain subject to examination | 2025 |
| France | |
| Income taxes | |
| Tax years remain subject to examination | 2022 2023 2024 2025 |
| Japan | |
| Income taxes | |
| Tax years remain subject to examination | 2025 |
| Taiwan | |
| Income taxes | |
| Tax years remain subject to examination | 2025 |
| USA | |
| Income taxes | |
| Tax years remain subject to examination | 2025 |