Retirement benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Components of net periodic benefit costs [Abstract]
Total net periodic pension costs (income)	$ (47)	$ (36)	$ (92)	$ (72)
Employer cash contributions to defined benefit pension plans			19
Expected employer cash contributions to defined benefit plan in current fiscal year	20		20
Selling, general and administrative expenses
Components of net periodic benefit costs [Abstract]
Service costs	2	0	3	1
Other income
Components of net periodic benefit costs [Abstract]
Interest costs	35	36	68	72
Expected returns on plan assets/other	(83)	(73)	(163)	(144)
United States
Components of net periodic benefit costs [Abstract]
Profit sharing provision expense	55	55	112	113
Foreign Plan
Components of net periodic benefit costs [Abstract]
Cost recognized in the consolidated condensed statements of earnings	$ 26	$ 27	$ 52	$ 54