Retirement benefits - components of net periodic pension costs (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2024	Aug. 31, 2023	Aug. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income, net	Other income, net	Other income, net
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	Other income, net
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs (Selling, general and administrative expenses)	$ 4	$ 4	$ 5
Interest costs (Other income, net)	276	264	149
Expected returns on plan assets/other (Other income, net)	(284)	(340)	(280)
Total net periodic pension income	(4)	(72)	(126)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	262	730	(251)
Prior service cost	(273)	(1)	(1)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ (11)	$ 729	$ (252)