Other intangible assets - Narrative (Details) - USD ($)	12 Months Ended
	Jul. 31, 2024	Jul. 31, 2023	Jul. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 173,000,000	$ 173,000,000	$ 161,000,000
Asset impairment charge	$ 0	$ 125,000,000	$ 0
Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration]		Asset impairment charge
Software
Finite-Lived Intangible Assets [Line Items]
Impairment charges		$ 107,000,000