Retirement benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Components of net periodic benefit costs [Abstract]
Total net periodic pension costs (income)	$ (35)	$ (13)	$ (69)	$ (23)
Employer cash contributions to defined benefit pension plans			10
Expected employer cash contributions to defined benefit plan in current fiscal year	22		22
Selling, general and administrative expenses
Components of net periodic benefit costs [Abstract]
Service costs	1	1	2	2
Other income (expense)
Components of net periodic benefit costs [Abstract]
Interest costs	37	50	72	99
Expected returns on plan assets/other	(73)	(64)	(144)	(124)
UNITED STATES
Components of net periodic benefit costs [Abstract]
Profit sharing provision expense	55	64	113	125
Foreign Plan
Components of net periodic benefit costs [Abstract]
Cost recognized in the consolidated condensed statements of earnings	$ 29	$ 33	$ 67	$ 64