Significant capital and funding transactions - Summary of Common Shares Issued (Detail) - CAD ($) shares in Thousands, $ 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] | ||||
| Issued in connection with share-based compensation plans | $ 3 | $ 6 | $ (69) | $ 19 |
| Purchased for cancellation | $ (1,673) | $ (488) | $ (2,633) | $ (826) |
| Ordinary shares [member] | ||||
| Disclosure of classes of share capital [line items] | ||||
| Issued in connection with share-based compensation plans, shares | 248 | 158 | 652 | 374 |
| Purchased for cancellation, shares | (7,386) | (3,013) | (11,611) | (4,955) |
| Increase (decrease) in number of ordinary shares issued, shares | (7,138) | (2,855) | (10,959) | (4,581) |
| Issued in connection with share-based compensation plans | $ 26 | $ 14 | $ 70 | $ 36 |
| Purchased for cancellation | (110) | (45) | (173) | (74) |
| Increase (decrease) in equity | $ (84) | $ (31) | $ (103) | $ (38) |