v3.26.1
Retirement benefit obligations - Sensitivity analysis (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
United Kingdom      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Contribution to the plan $ 0.0 $ 0.0 $ 0.0
Supplementary payments 0.0 0.0 0.0
United States of America      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Contribution to the plan 0.0 0.0 0.0
Supplementary payments $ 0.0 $ 0.0 $ 0.0
Pension plans | United Kingdom | Discount rate and inflation rate      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Percentage of reasonably possible increase in actuarial assumption 0.50%    
Percentage of reasonably possible decrease in actuarial assumption 0.50%    
Pension plans | United Kingdom | Discount rate      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Pension obligation +50bps/+1yr $ (25.0)    
Pension obligation -50bps/-1yr 28.0    
Pension plans | United Kingdom | Inflation      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Pension obligation +50bps/+1yr 21.5    
Pension obligation -50bps/-1yr $ (19.4)    
Pension plans | United Kingdom | Mortality      
Disclosure of sensitivity analysis for actuarial assumptions [line items]      
Reasonably possible increase in life expectancy measured in period of time 1 year    
Reasonably possible decrease in life expectancy measured in period of time 1 year    
Pension obligation +50bps/+1yr $ 18.0    
Pension obligation -50bps/-1yr $ (18.0)