Share-based compensation - Schedule of Expense (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2025	Apr. 30, 2024
Share-Based Payment Arrangement [Abstract]
Share-based compensation expense (within SG&A)	$ 9	$ 15	$ 22	$ 39
Income tax benefit	$ 2	$ 4	$ 6	$ 10

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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