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

The amounts recognised for transaction recognised separately from the acquisition of assets and the assumption of liabilities in business combinations. [Refer: Total for all business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2025-01-01
-Paragraph B64
-Subparagraph l
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2025-en-r&anchor=para_B64_l_iii&doctype=Appendix&subtype=B
-URIDate 2025-03-27

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration