Retirement benefits - narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Reduction in benefit obligation due to potential discount rate decrease	$ 159
Reduction in benefit obligation due to potential expected return decrease	14
Cash contributions to defined benefit pension plans	18
Postretirement Health Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan obligation	113	$ 122
Expected benefit to be paid next fiscal year	8
United States
Defined Benefit Plan Disclosure [Line Items]
Profit sharing provision expense	239	234	$ 221
Contributions to profit sharing	241	236	222
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Cost recognized in the consolidated condensed statements of earnings	$ 83	$ 90	$ 101