Summary of significant accounting policies - Supplier Finance Program (Details) $ in Millions	12 Months Ended
Jul. 31, 2025 USD ($)
Supplier Finance Program, Obligation [Roll Forward]
Beginning balance	$ 46
Invoices confirmed during the year	390
Confirmed invoices paid during the year	(374)
Ending balance	$ 62

Amount of obligation for supplier finance program, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-4

+ Details

Name:	us-gaap_SupplierFinanceProgramObligationCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of decrease in obligation for supplier finance program from settlement.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 55
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477128/405-50-55-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

+ Details

Name:	us-gaap_SupplierFinanceProgramObligationDecreaseSettlement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase in obligation for supplier finance program.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 55
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477128/405-50-55-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

+ Details

Name:	us-gaap_SupplierFinanceProgramObligationIncrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_SupplierFinanceProgramObligationRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration