Retirement benefits - Schedule of Net Periodic Pension Income (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2024	Nov. 30, 2023
Retirement Benefits [Abstract]
Service costs	$ 2	$ 1
Interest costs	63	70
Expected returns on plan assets/other	(63)	(73)
Total net periodic pension cost (income)	$ 3	$ (3)