Retirement benefit obligations - Net Periodic Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2025	Jul. 31, 2024	Jul. 31, 2023
Other expense (income), net
Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income	Other income (expense), net
Amortization of net actuarial losses	$ 15	$ 15	$ 11
Interest cost	62	62	51
Expected return on plan assets	(65)	(63)	(49)
Net periodic cost	$ 12	$ 14	$ 13
Weighted average assumptions:
Discount rate, net periodic benefit cost (percent)	4.98%	5.05%	3.53%
Discount rate, benefit obligations (percent)	5.71%	4.98%	5.05%
Expected return on plan assets (percent)	5.02%	5.11%	3.41%
Wage inflation growth rate (percent)	2.40%	2.45%	2.50%