Retirement benefits - Narrative (Details) $ in Millions			3 Months Ended		6 Months Ended
	Dec. 07, 2023 USD ($)	Nov. 23, 2023 USD ($) member	Feb. 29, 2024 USD ($)	Feb. 28, 2023 USD ($)	Feb. 29, 2024 USD ($)	Feb. 28, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Accelerated future employer contributions		$ 210
Contributions by employer	$ 375
Plan assets, period increase					$ 127
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Profit sharing provision expense			$ 51	$ 60	111	$ 125
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Cost recognized in the consolidated condensed statements of earnings			$ 24	$ 21	$ 46	$ 41
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Number of members | member		53,000
Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected future employer contributions		$ 760
Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected future employer contributions		$ 820