Retirement benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2023	Feb. 28, 2022	Feb. 28, 2023	Feb. 28, 2022
Components of net periodic benefit costs [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense), net		Other income (expense), net
Interest costs	$ 63	$ 38	$ 122	$ 78
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense), net		Other income (expense), net
Expected returns on plan assets/other	$ (80)	(72)	$ (156)	(146)
Total net periodic pension income	(16)	(33)	(32)	(65)
Employer cash contributions to defined benefit pension plans			11
Expected employer cash contributions to defined benefit plan in current fiscal year	25		25
Selling, general and administrative expense
Components of net periodic benefit costs [Abstract]
Service costs	1	1	2	3
U.S. Retail Pharmacy
Components of net periodic benefit costs [Abstract]
Profit sharing provision expense	60	54	125	123
Foreign Plan
Components of net periodic benefit costs [Abstract]
Cost recognized in the consolidated condensed statements of earnings	$ 21	$ 23	$ 41	$ 48