v3.25.4
Employee benefit obligations - Schedule of Present Value Defined Benefit Obligation (Details) - CHF (SFr)
SFr in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of defined benefit plans [line items]    
Employee benefit obligations at January 1 SFr 8.6 SFr 2.2
Actuarial (losses)/gains from    
Employee benefit obligations at December 31 5.5 8.6
Present value of defined benefit obligation    
Disclosure of defined benefit plans [line items]    
Employee benefit obligations at January 1 52.9 35.3
Current service cost 8.6 5.3
Contributions by the employees 5.5 4.3
Interest expenses 0.5 0.5
Past service cost (0.3) 0.0
Benefits paid 1.7 2.8
Actuarial (losses)/gains from    
changes in financial assumptions (4.2) 2.5
changes in experience adjustments 0.7 2.1
Employee benefit obligations at December 31 SFr 65.4 SFr 52.9