ENVIRONMENTAL LIABILITIES - Summary of Movements in Environmental Liabilities (Details) - CAD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Accrual for Environmental Loss Contingencies [Roll Forward] | ||
| Environmental liabilities - beginning | $ 47 | $ 79 |
| Expenditures | (5) | (37) |
| Revaluation adjustment | 2 | 5 |
| Environmental liabilities - ending | 44 | 47 |
| Less: current portion | (7) | (11) |
| Environmental liabilities non current portion | 37 | 36 |
| PCB | ||
| Accrual for Environmental Loss Contingencies [Roll Forward] | ||
| Environmental liabilities - beginning | 6 | 39 |
| Expenditures | (4) | (34) |
| Revaluation adjustment | (1) | 1 |
| Environmental liabilities - ending | 1 | 6 |
| Less: current portion | (1) | (6) |
| Environmental liabilities non current portion | 0 | 0 |
| LAR | ||
| Accrual for Environmental Loss Contingencies [Roll Forward] | ||
| Environmental liabilities - beginning | 41 | 40 |
| Expenditures | (1) | (3) |
| Revaluation adjustment | 3 | 4 |
| Environmental liabilities - ending | 43 | 41 |
| Less: current portion | (6) | (5) |
| Environmental liabilities non current portion | $ 37 | $ 36 |