Retirement benefits - Schedule of Net Periodic Pension Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2024	May 31, 2023
Retirement Benefits [Abstract]
Service costs	$ 1	$ 1	$ 3	$ 3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income, net		Other income, net
Interest costs	$ 68	64	$ 202	186
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income, net		Other income, net
Expected returns on plan assets/other	$ (70)	(81)	$ (206)	(237)
Total net periodic pension income	$ (1)	$ (17)	$ (1)	$ (48)