Intangible assets - Narrative (Details) - CHF (SFr) SFr in Millions |
6 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Disclosure of detailed information about intangible assets [line items] | ||||
| Intangible assets | SFr 55.8 | SFr 55.3 | SFr 54.2 | SFr 58.3 |
| Research and development expense | 5.4 | SFr 3.6 | ||
| Impairment loss recognised in profit or loss, goodwill | 0.0 | 0.0 | ||
| Goodwill expected to be deductible for tax purposes | 0.0 | |||
| Intangible assets under development | ||||
| Disclosure of detailed information about intangible assets [line items] | ||||
| Intangible assets | SFr 0.6 | SFr 0.3 | ||