v3.26.1
Other Long-Term Assets - Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2025
CAD ($)
bbl
Dec. 31, 2024
CAD ($)
Dec. 31, 2023
CAD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Disclosure of joint ventures [line items]          
Borrowings $ 16,617,000,000 $ 18,819,000,000      
(Repayment) issuance of bank credit facilities and commercial paper, net $ 1,395,000,000 (5,466,000,000) $ 0    
Commercial Paper          
Disclosure of joint ventures [line items]          
Borrowings       $ 0 $ 467
Maximum credit facility       $ 2,500  
North West Redwater Partnership          
Disclosure of joint ventures [line items]          
Toll payer percent for others 75.00%        
North West Redwater Partnership          
Disclosure of joint ventures [line items]          
Company's voting percent interest in joint venture 50.00%        
Processing agreement, barrels of bitumen feedstock per date for the Company | bbl 12,500        
Percent of pro rata share of debt company has committed paying to joint venture, toll payer percent 25.00%        
Processing agreement, barrels of bitumen feedstock per date for others | bbl 37,500        
Term of commitment to joint venture 40 years        
Investments in joint ventures $ 0        
Cumulative unrecognised share of losses of joint ventures 496,000,000 509,000,000      
Recovery of unrecognised share of losses of joint ventures $ 13,000,000 46,000,000      
Unrecognised share of losses of joint ventures     $ 4,000,000    
North West Redwater Partnership | North West Redwater Partnership          
Disclosure of joint ventures [line items]          
Barrels of bitumen feedstock processed per day output capacity (approximately) | bbl 80,000        
Barrels of bitumen feedstock processed per day | bbl 50,000        
Borrowings $ 8,750,000,000 8,750,000,000      
North West Redwater Partnership | North West Redwater Partnership | Commercial Paper          
Disclosure of joint ventures [line items]          
Borrowings 1,583,000,000 1,459,000,000      
North West Redwater Partnership | North West Redwater Partnership | Syndicated Credit Facility          
Disclosure of joint ventures [line items]          
Maximum credit facility 1,900,000,000 1,900,000,000      
Reduction in maximum borrowing capacity   275,000,000      
North West Redwater Partnership | North West Redwater Partnership | Syndicated Credit Facility, Non-Revolving          
Disclosure of joint ventures [line items]          
Maximum credit facility   250,000,000      
(Repayment) issuance of bank credit facilities and commercial paper, net 250,000,000        
Repayments of line of credit facility   657,000,000      
North West Redwater Partnership | North West Redwater Partnership | Series A Bonds          
Disclosure of joint ventures [line items]          
Repayments of credit facility   $ 500,000,000      
Borrowings, interest rate   3.20%     3.20%
North West Redwater Partnership | North West Redwater Partnership | Series P Bonds Due June 2034          
Disclosure of joint ventures [line items]          
Maximum credit facility   $ 700,000,000      
Borrowings, interest rate   4.85%     4.85%
North West Redwater Partnership | North West Redwater Partnership | Series Q Bonds Due June 2054          
Disclosure of joint ventures [line items]          
Maximum credit facility   $ 600,000,000      
Borrowings, interest rate   5.08%     5.08%
North West Redwater Partnership | North West Redwater Partnership | Short term demand operating facility          
Disclosure of joint ventures [line items]          
Borrowings 50,000,000 $ 103,000,000      
Maximum credit facility $ 300,000,000 $ 300,000,000