v3.26.1
RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Schedule of Significant Unobservable Inputs Used in the Fair Value Measurement of Level 3 Derivative Instruments (Details)
$ in Millions
Jun. 30, 2026
CAD ($)
$ / MMBTU
$ / bbl
$ / MWh
Dec. 31, 2025
CAD ($)
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ (1,318) $ (823)
Fair Value    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ (1,318) (823)
Level 3    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ 179  
Level 3 | Fair Value    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ 179 $ 188
Commodity Options | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 11  
Commodity Options | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 74  
Commodity Options | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 53  
Natural gas | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 3.43  
Natural gas | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 8.88  
Natural gas | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 4.56  
Natural gas | Commodity Contracts - Financial | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ 6  
Natural gas | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 0.84  
Natural gas | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 15.9  
Natural gas | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 4.36  
Natural gas | Commodity Contracts - Physical | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ (5)  
Natural gas | Commodity Options | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 3.5  
Natural gas | Commodity Options | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 13.81  
Natural gas | Commodity Options | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) 7.83  
Natural gas | Commodity Options | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ 106  
Crude | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 137.3  
Crude | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 168.02  
Crude | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 160.84  
Crude | Commodity Contracts - Financial | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ 35  
Crude | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 57.68  
Crude | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 146.65  
Crude | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / bbl 97.27  
Crude | Commodity Contracts - Physical | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ 63  
Power | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 26.62  
Power | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 224.19  
Power | Commodity Contracts - Financial | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 84.5  
Power | Commodity Contracts - Financial | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ (4)  
Power | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Minimum Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 39.16  
Power | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Maximum Price/ Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 417.94  
Power | Commodity Contracts - Physical | Level 3 | Market Approach Valuation Technique | Weighted Average Price/Volatility    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Price volatility (in $/MMBTU, $/barrel, $ / MW/H, percent) | $ / MWh 89.74  
Power | Commodity Contracts - Physical | Level 3 | Fair Value | Market Approach Valuation Technique    
Significant unobservable inputs used in the fair value measurement of Level 3 derivative instruments    
Fair Value | $ $ (22)