Significant capital and funding transactions - Summary of Common Shares Issued (Parenthetical) (Detail) - Ordinary shares [member] - CAD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 12, 2026 |
Jun. 11, 2026 |
Jul. 31, 2026 |
Jul. 31, 2025 |
Jul. 31, 2026 |
Jul. 31, 2025 |
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| Disclosure of classes of share capital [line items] | ||||||
| Common Shares Purchased | 45 | 35 | ||||
| Average cost of shares purchased for cancellation | $ 285.33 | $ 175.27 | $ 245.88 | $ 171.22 | ||
| Fair value of common shares purchased | $ 1,603 | $ 955 | $ 4,236 | $ 1,781 | ||
| Book value of common shares purchased | $ 84 | $ 81 | $ 257 | $ 155 | ||
| Average book value per share | $ 14.96 | $ 14.88 | $ 14.93 | $ 14.87 | ||