ENVIRONMENTAL LIABILITIES - Additional Information (Details) - CAD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Environmental Liabilities [Line Items] | ||
| Increase (decrease) of environmental liability due to revaluation adjustment | $ 2 | $ 5 |
| PCB | ||
| Environmental Liabilities [Line Items] | ||
| Undiscounted environmental liabilities | 1 | 6 |
| Increase (decrease) of environmental liability due to revaluation adjustment | (1) | 1 |
| LAR | ||
| Environmental Liabilities [Line Items] | ||
| Undiscounted environmental liabilities | 43 | 41 |
| Increase (decrease) of environmental liability due to revaluation adjustment | $ 3 | $ 4 |