v3.25.4
Financial instruments - Narrative (Details)
$ in Millions
12 Months Ended
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2026
USD ($)
Disclosure of financial assets [line items]      
Financial assets $ 469 $ 948  
Borrowings 371 265  
Increase (Decrease) In Interest Expense On Borrowings $ 2 0  
Increase (Decrease) In Future Electricity Prices, Percent 10.00%    
Gain (Loss) On Electricity Swaps Related To Future Electricity Prices $ 18    
Forecast      
Disclosure of financial assets [line items]      
Contractual commitments for acquisition of property, plant and equipment     $ 51
United States of America, Dollars      
Disclosure of financial assets [line items]      
Change in value of earnings, increase (decrease) of one cent increase (decrease) 19    
Change in value of foreign currency, increase (decrease) of one cent increase (decrease) 7    
Canada, Dollars      
Disclosure of financial assets [line items]      
Change in value of earnings, increase (decrease) of one cent increase (decrease) 19    
Change in value of foreign currency, increase (decrease) of one cent increase (decrease) 7    
United Kingdom, Pounds      
Disclosure of financial assets [line items]      
Change in value of foreign currency, increase (decrease) of one cent increase (decrease) 7    
Euro Member Countries, Euro      
Disclosure of financial assets [line items]      
Change in value of foreign currency, increase (decrease) of one cent increase (decrease) 7    
Electricity Swaps      
Disclosure of financial assets [line items]      
Financial assets 24    
Long-term debt   (14)  
Trade receivables      
Disclosure of financial assets [line items]      
Financial assets $ 244 $ 292  
Trade receivables | Credit risk      
Disclosure of financial assets [line items]      
Credit risk 0.34 0.29