v3.26.1
Earnings per share - Schedule of Earnings per Share (Details) - CAD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Earnings Per Share [Abstract]        
Net income attributable to controlling shareholders $ 1,024 $ 1,234 $ 1,870 $ 2,144
Weighted-average basic shares outstanding (in shares) 886.4 923.8 891.6 928.4
Dilutive effect of stock options (in shares) 0.7 1.0 0.6 1.1
Weighted-average diluted shares outstanding (in shares) 887.1 924.8 892.2 929.5
Earnings per share - basic (in dollars per share) $ 1.16 $ 1.34 $ 2.10 $ 2.31
Earnings per share - diluted (in dollars per share) $ 1.15 $ 1.33 $ 2.10 $ 2.31