Income tax - Earnings Before Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2024	Jul. 31, 2023	Jul. 31, 2022
Investments, Owned, Federal Income Tax Note [Line Items]
United Kingdom	$ 80	$ 80	$ 102
Income before income taxes	2,464	2,464	2,708
Foreign, United States
Investments, Owned, Federal Income Tax Note [Line Items]
Foreign	2,022	2,011	2,222
Foreign, Excluding United States
Investments, Owned, Federal Income Tax Note [Line Items]
Foreign	$ 362	$ 373	$ 384