EMPLOYEE BENEFITS OBLIGATIONS - Employee Benefit Obligation (Details) - CAD ($) $ in Millions |
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|---|---|---|---|
| Disclosure of defined benefit plans [line items] | |||
| Employee benefits obligations - net | $ (122.5) | $ (33.0) | |
| Employee benefit assets | (11.6) | (65.7) | |
| Employee benefit obligations | 134.1 | 98.7 | |
| Funded plans | |||
| Disclosure of defined benefit plans [line items] | |||
| Employee benefits obligations - net | (13.3) | 65.7 | |
| Funded and unfunded defined benefit pension obligations | Funded plans | |||
| Disclosure of defined benefit plans [line items] | |||
| Employee benefits obligations - net | (599.2) | (476.3) | $ (590.7) |
| Funded and unfunded defined benefit pension obligations | Unfunded plans | |||
| Disclosure of defined benefit plans [line items] | |||
| Employee benefits obligations - net | (109.2) | (98.7) | (91.8) |
| Fair value of plan assets | Funded plans | |||
| Disclosure of defined benefit plans [line items] | |||
| Employee benefits obligations - net | $ 585.9 | $ 542.0 | $ 641.7 |