v3.26.1
Financial Instruments - Carrying Amounts and Reconciliation of Derivative Financial Instruments (Details)
$ in Millions
5 Months Ended 12 Months Ended
Dec. 31, 2025
USD ($)
MMBTU
Dec. 31, 2026
USD ($)
MMBTU
Dec. 31, 2025
USD ($)
MMBTU
Dec. 31, 2024
USD ($)
MMBTU
Dec. 31, 2025
CAD ($)
Dec. 31, 2024
CAD ($)
Dec. 31, 2023
CAD ($)
Disclosure of detailed information about hedging instruments [line items]              
Derivatives held for trading         $ (65) $ 5  
Current portion of other long-term assets         0 13  
Current portion of other long-term liabilities         (8) (8)  
Other long-term liabilities         57 0  
Derivative financial asset (liability), net         (65) 5 $ 9
Derivative, volume per day | MMBTU       50,000      
Derivative, AECO fixed price       $ 1.82      
Derivative Contract One              
Disclosure of detailed information about hedging instruments [line items]              
Derivative, volume per day | MMBTU 12,500   12,500        
Derivative, AECO fixed price $ 1.30   $ 1.47        
Derivative Contract Two              
Disclosure of detailed information about hedging instruments [line items]              
Derivative, volume per day | MMBTU   25,000 25,000        
Derivative, AECO fixed price   $ 2.16 $ 1.82        
Natural Gas              
Disclosure of detailed information about hedging instruments [line items]              
Derivatives held for trading         (4) 7  
Natural gas embedded derivative              
Disclosure of detailed information about hedging instruments [line items]              
Derivatives held for trading         (57) 0  
Foreign currency forward contracts              
Disclosure of detailed information about hedging instruments [line items]              
Derivatives held for trading         $ (4) $ (2)