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Earnings per share (Details) - CAD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024
Earnings per share [line items] |  |
Basic net earnings | $ 1,658,285 | $ 1,692,715
Diluted net earnings | $ 1,658,285 | $ 1,692,715
Basic weighted average number of ordinary shares outstanding (in shares) | 222,693,319 | 228,074,108
Dilutive net effect of all instruments on weighted average number of ordinary shares (in shares) | 2,796,025 | 3,598,753
Diluted weighted average number of ordinary shares outstanding (in shares) | 225,489,344 | 231,672,861
Basic earnings per share (CAD per share) | $ 7.45 | $ 7.42
Diluted earnings per share (CAD per share) | $ 7.35 | $ 7.31
Class A subordinate voting shares | Capital stock |  |
Earnings per share [line items] |  |
Anti-dilutive securities excluded from computation of earnings per share (in shares) | 2,247,354 | 6,528,608
PSUs | Class A subordinate voting shares | Capital stock |  |
Earnings per share [line items] |  |
Anti-dilutive securities excluded from computation of earnings per share (in shares) | 8,861,543 | 2,601,356

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- Definition The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2025-01-01 -Paragraph 70 -Subparagraph b -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_70_b&doctype=Standard -URIDate 2025-03-27 + Details
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- Definition The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2025-01-01 -Paragraph 66 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_66&doctype=Standard -URIDate 2025-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2025-01-01 -Paragraph 67 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_67&doctype=Standard -URIDate 2025-03-27 + Details
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- Definition The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2025-01-01 -Paragraph 66 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_66&doctype=Standard -URIDate 2025-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2025-01-01 -Paragraph 67 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_67&doctype=Standard -URIDate 2025-03-27 + Details
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