v3.26.1
financial instruments - Significant unobservable inputs used in the fair value measurement (Details) - CAD ($)
$ in Millions
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Disclosure of fair value measurement of assets        
Balance of period $ 56,812   $ 59,613  
Virtual power purchase agreements unrealized change in forward element | At fair value        
Disclosure of fair value measurement of assets        
Included in net income, excluding income taxes 3 $ 2    
Included in other comprehensive income, excluding income taxes (21) 17    
Balance of period $ (46) $ (19) $ (28) $ (38)