v3.25.4
Financial instruments (Foreign Exchange Forward Contracts) (Details) - Foreign Exchange Forward
$ in Millions
12 Months Ended
Dec. 31, 2025
CAD ($)
Dec. 31, 2024
CAD ($)
Dec. 31, 2023
CAD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2025
CAD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2024
CAD ($)
Foreign Currency Derivatives [Abstract]              
Notional amount       $ 477,000,000   $ 580,000,000  
Weighted-average exchange rate       1.39 1.39 1.37 1.37
Weighted average term 110 days 88 days          
Loss on derivative instruments, net, pretax $ 37   $ 45        
Gain on derivative instruments, net, pretax   $ 226          
Other Current Assets              
Foreign Currency Derivatives [Abstract]              
Derivative asset, fair value         $ 0   $ 38
Accounts Payable and Other              
Foreign Currency Derivatives [Abstract]              
Derivative liability, fair value         $ 10   $ 0