v3.26.1
Income Taxes - Narrative (Details) - CAD ($)
$ in Millions
 12 Months Ended
Nov. 01, 2025
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Scotford and Quest        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deferred tax expense relating to gain (loss) on disposition   $ 107    
Disposal of business, ownership interest   10.00%    
ASOP Mines        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deferred tax expense relating to gain (loss) on remeasurement of interest   $ 1,037    
Disposal of business, ownership interest 90.00%      
Unused tax losses        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deductible temporary differences for which no deferred tax asset is recognised   1,000    
Unused tax credits        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deductible temporary differences for which no deferred tax asset is recognised   950    
Ninian Field In The North Sea and T-Block Assets | North Sea        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deferred corporate income tax recovery   165    
Ninian Field in the North Sea | North Sea        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Deferred corporate income tax recovery     $ 50 $ 118
Deferred PRT – North Sea   $ (461) $ (89) $ (205)