v3.26.1
Other employee benefits (Narrative) (Details) - Other employee benefits [Member]
$ in Millions
 12 Months Ended
Dec. 31, 2025
USD ($)
Year
Dec. 31, 2024
Year
Other Employee Benefits [Line Items]    
Weighted average duration of non-pension post employment obligation | Year 14.4 15
Actuarial assumption of discount rates [Member]    
Other Employee Benefits [Line Items]    
Reasonably possible increase in actuarial assumption, basis points 50  
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption $ (5.7)  
Reasonably possible decrease in actuarial assumption, basis points 50  
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption $ 6.4  
Actuarial assumption of health care cost trend rates [Member]    
Other Employee Benefits [Line Items]    
Percentage of reasonably possible increase in actuarial assumption 1.00%  
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption $ 12.9  
Percentage of reasonably possible decrease in actuarial assumption 1.00%  
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption $ (10.4)  
Actuarial assumptions of life expectancy [Member]    
Other Employee Benefits [Line Items]    
Reasonably possible increase in life expectancy (years) | Year 1  
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption $ 3.2  
Reasonably possible decrease in life expectancy (years) | Year 1  
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption $ (3.2)  
Active members [Member]    
Other Employee Benefits [Line Items]    
Weighted average duration of non-pension post employment obligation | Year 22.3 23
Inactive members [Member]    
Other Employee Benefits [Line Items]    
Weighted average duration of non-pension post employment obligation | Year 10.9 11.3