Restructuring, acquisition and related integration costs (Details) - CAD ($) |
12 Months Ended | 18 Months Ended | |
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Mar. 31, 2024 |
|
| Analysis of income and expense [abstract] | |||
| Restructuring | $ 196,796,000 | $ 0 | |
| Cost optimization program | 0 | 91,063,000 | $ 100,027,000 |
| Acquisition and related integration costs | 88,235,000 | 5,866,000 | |
| Restructuring, acquisition and related integration costs | $ 285,031,000 | $ 96,929,000 | |