Share-based compensation - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended
Oct. 31, 2025 USD ($) shares	Oct. 31, 2025 USD ($) shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based payment, cost not yet recognized \| $	$ 96	$ 96
Share based payment, cost not yet recognized, period for recognition (in years)		2 years 1 month 6 days
Options granted (in shares)	25,135
Stock options outstanding (in shares)	63,523	63,523
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-EX granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)		3 years
PSU single metric
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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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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Number of options outstanding, including both vested and non-vested options.

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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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