Share-based compensation - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended
Oct. 31, 2024 USD ($) shares	Oct. 31, 2024 USD ($)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based payment, cost not yet recognized \| $	$ 112	$ 112
Share based payment, cost not yet recognized, period for recognition (in years)		2 years 6 months
Options granted (in shares) \| shares	65,760
RSU awards granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)		3 years
PSU awards granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)		3 years
PSU-EX granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)		3 years
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)	3 years
Service period	1 year
Expiration period	10 years

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Gross number of share options (or share units) granted during the period.

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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