v3.25.4
Personnel expenses - Disclosure of Conditions and Inputs Used in the Measurement of the Fair Values at Grant Dates (Details)
 12 Months Ended
Dec. 31, 2025
shares
SFr / shares
Dec. 31, 2024
shares
SFr / shares
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Number of RSU and PSU granted (in shares) | shares 2,005,764 1,882,880
Weighted average exercise price (in CHF per share) SFr 0.10 SFr 0.10
Expected dividend 0 0
Weighted average fair value of rights granted (in CHF per share) SFr 3.15 SFr 3.43
Restricted Share Units (RSU)    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Number of RSU and PSU granted (in shares) | shares 191,760 192,639
Vesting period 1 year 1 year
Performance Share Units (PSU)    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Number of RSU and PSU granted (in shares) | shares 1,814,004 1,690,241
Performance Share Units (PSU), Management Board    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Vesting period 3 years 3 years
Minimum    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Share price (in CHF per share) SFr 2.90 SFr 3.38
Expected volatility on Common shares 59.10% 66.87%
Risk free interest rate, common shares 0.35% 1.47%
Expected volatility on NBI 19.74% 21.93%
Risk free interest rate, NBI 3.63% 3.82%
Expected volatility on SPI 12.07% 12.72%
Risk free interest rate, SPI 0.35% 1.47%
Minimum | Restricted Share Units (RSU)    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Full contractual life for RSU and PSU 3 years 3 years
Minimum | Performance Share Units (PSU), Employees excluding Management Board    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Vesting period 3 years 3 years
Maximum    
Disclosure Of Number And Weighted Average Exercise Prices Of Other Equity Instruments [Line Items]    
Share price (in CHF per share) SFr 4.06 SFr 6.57
Expected volatility on Common shares 70.46% 72.79%
Risk free interest rate, common shares 1.30% 1.65%
Expected volatility on NBI 21.89% 23.14%
Risk free interest rate, NBI 4.18% 5.21%
Expected volatility on SPI 13.28% 13.07%
Risk free interest rate, SPI 1.30% 1.65%