Summary of significant accounting policies - Advertising and Marketing Costs (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 31, 2025	Jul. 31, 2024	Jul. 31, 2023
Accounting Policies [Abstract]
Net advertising and marketing costs	$ 376	$ 380	$ 403

The total expense recognized in the period for promotion, public relations, and brand or product advertising.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

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