Foreign currency risk - Narrative (Details) - CHF (SFr) SFr in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
|
| Disclosure of Financial Risk Management [Abstract] | |||
| Net Derivative Financial Assets (Liabilities) | SFr 0.0 | SFr 0.0 | |
| Change in fair value of foreign exchange derivatives | SFr 0.0 | SFr 0.0 | SFr 1.4 |