Significant capital and funding transactions - Summary of Common Shares Issued (Parenthetical) (Detail) - Ordinary shares [member] - CAD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Apr. 30, 2026 |
Apr. 30, 2025 |
Apr. 30, 2026 |
Apr. 30, 2025 |
|
| Disclosure of classes of share capital [line items] | ||||
| Average cost of shares purchased for cancellation | $ 226.5 | $ 162.1 | $ 226.79 | $ 166.76 |
| Fair value of common shares purchased | $ 1,673 | $ 488 | $ 2,633 | $ 826 |
| Book value of common shares purchased | $ 110 | $ 45 | $ 173 | $ 74 |
| Average book value per share | $ 14.93 | $ 14.87 | $ 14.92 | $ 14.86 |