FAIR VALUE OF FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Summary of Fair Values and Carrying Values of Long-Term Debt (Details) - CAD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Carrying Value	$ 19,017	$ 17,479
Fair Value	$ 18,721	$ 17,364

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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+ Details

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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+ Details