Related party transactions - Summary of Stock Options, Stock Awards and Shares Held by Key Management Personnel, Directors and Their Close Family Members ( Parenthetical) (Detail) $ in Millions |
Oct. 31, 2022
CAD ($)
shares
|
Oct. 31, 2021
CAD ($)
shares
|
|---|---|---|
| Disclosure of transactions between related parties [line items] | ||
| Number of stock options, stock awards and shares held by key management personnel, Directors and their close family members | shares | 569,470 | 21,723 |
| Value of stock options, stock awards and shares held by key management personnel, Directors and their close family members | $ | $ 34 | $ 3 |