| CHF million | 
 | Share capital | 
 | Additional paid-in capital | 
 | Retained earnings | 
 | Treasury shares | 
 | Cumul. translation adjustm. | 
 | Minority interests | 
 | Total equity | 
| Balance at 31.12.2024 | 
 | 0.4 | 
 | 811.3 | 
 | –464.2 | 
 | –5.6 | 
 | –70.7 | 
 | 98.7 | 
 | 369.9 | 
| Net profit for the reporting period | 
 | 
 | 
 | 
 | 
 | 50.4 | 
 | 
 | 
 | 
 | 
 | 46.3 | 
 | 96.7 | 
| Currency translation adjustments | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | –1.4 | 
 | –4.1 | 
 | –5.5 | 
| Dividend paid | 
 | 
 | 
 | 
 | 
 | –33.5 | 
 | 
 | 
 | 
 | 
 | –30.1 | 
 | –63.6 | 
| Shares awarded (share-based compensation) | 
 | 
 | 
 | 
 | 
 | –0.1 | 
 | 3.2 | 
 | 
 | 
 | –0.1 | 
 | 3.0 | 
| Treasury shares (purchased) re-issued | 
 | 
 | 
 | 
 | 
 | 
 | 
 | –3.1 | 
 | 
 | 
 | 
 | 
 | –3.1 | 
| Balance at 01.07.2024 | 
 | 0.4 | 
 | 811.3 | 
 | –481.0 | 
 | –5.7 | 
 | –69.3 | 
 | 86.7 | 
 | 342.4 | 
| Balance at 31.12.2023 | 
 | 0.4 | 
 | 811.3 | 
 | –499.3 | 
 | –6.9 | 
 | –79.2 | 
 | 60.5 | 
 | 286.8 | 
| Net profit for the reporting period | 
 | 
 | 
 | 
 | 
 | 24.9 | 
 | 
 | 
 | 
 | 
 | 23.6 | 
 | 48.5 | 
| Currency translation adjustments | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | –11.9 | 
 | –14.1 | 
 | –26.0 | 
| Dividend paid | 
 | 
 | 
 | 
 | 
 | –39.8 | 
 | 
 | 
 | 
 | 
 | –33.1 | 
 | –72.9 | 
| Shares awarded (share-based compensation) | 
 | 
 | 
 | 
 | 
 | 0.2 | 
 | 2.2 | 
 | 
 | 
 | 0.2 | 
 | 2.6 | 
| Balance at 01.07.2023 | 
 | 0.4 | 
 | 811.3 | 
 | –484.6 | 
 | –9.1 | 
 | –67.3 | 
 | 83.9 | 
 | 334.6 |