v3.26.1
RISK MANAGEMENT FINANCIAL INSTRUMENTS - Schedule of Restricted Long-Term Investments And Cash Held In Trust (Details) - CAD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Fair Value, Option, Quantitative Disclosures [Line Items]          
Fair value of investments $ 1,483   $ 1,483   $ 1,293
Cost value of investments 1,275   1,275   1,170
Restricted Long Term Investment          
Fair Value, Option, Quantitative Disclosures [Line Items]          
Unrealized holding gains 96 $ 30 85 $ 46  
Fair Value, Inputs, Level 1 [Member]          
Fair Value, Option, Quantitative Disclosures [Line Items]          
Fair value of investments 1,030   1,030   877
Cost value of investments 819   819   744
Fair Value, Inputs, Level 2 [Member]          
Fair Value, Option, Quantitative Disclosures [Line Items]          
Fair value of investments 453   453   416
Cost value of investments $ 456   $ 456   $ 426