Employee Compensation - Pension and Other Employee Future Benefits - Summary of Pension and Other Employee Future Benefit Expenses (Parenthetical) (Detail) - CAD ($) $ in Millions	12 Months Ended
Oct. 31, 2025	Oct. 31, 2024
Other employee future benefit plans [Member]
Disclosure of defined benefit plans [line items]
Net interest (income) expense on effect of asset ceiling	$ 6	$ 3
Pension Plan [Member]
Disclosure of defined benefit plans [line items]
Net interest (income) expense on effect of asset ceiling	$ 0	$ 0

The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 141
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_b&doctype=Standard
-URIDate 2024-03-27

Name:	ifrs-full_InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration