Employee benefits - Pension and other post-employment benefits - Mortality Assumptions to Determine Benefit Obligation (Detail)	12 Months Ended
	Oct. 31, 2024	Oct. 31, 2023
Male [member] \| Canada [member] \| Retiring currently at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	23 years 2 months 12 days	23 years 10 months 24 days
Male [member] \| Canada [member] \| Currently aged 45 and retiring at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	24 years 2 months 12 days	24 years 9 months 18 days
Male [member] \| United Kingdom [member] \| Retiring currently at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	22 years 1 month 6 days	23 years 6 months
Male [member] \| United Kingdom [member] \| Currently aged 45 and retiring at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	23 years 4 months 24 days	24 years 8 months 12 days
Female [member] \| Canada [member] \| Retiring currently at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	24 years 4 months 24 days	24 years 3 months 18 days
Female [member] \| Canada [member] \| Currently aged 45 and retiring at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	25 years 3 months 18 days	25 years 2 months 12 days
Female [member] \| United Kingdom [member] \| Retiring currently at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	24 years 4 months 24 days	25 years 4 months 24 days
Female [member] \| United Kingdom [member] \| Currently aged 45 and retiring at age 65 [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Life expectancy for members	25 years 8 months 12 days	26 years 9 months 18 days