v3.26.1
Financial instruments (Details) - CAD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Schedule of Investments [Line Items]          
Long-term debt, excluding commercial paper $ 23,686   $ 23,686   $ 22,023
Long-term debt, fair value 22,182   22,182   $ 20,740
Net Investment Hedge          
Schedule of Investments [Line Items]          
Gain (loss) on net investment hedge $ (134) $ 299 $ (257) $ 305