FINANCIAL INSTRUMENTS - Additional Information (Details) - CAD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Disclosure of detailed information about financial instruments [Line Items] | ||
| Long-term debt | $ 8,547 | $ 11,032 |
| Level 2 of fair value hierarchy | ||
| Disclosure of detailed information about financial instruments [Line Items] | ||
| Debt, fair value | $ 7,800 | $ 10,600 |