Segment reporting - geographic data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Aug. 31, 2023	May 31, 2023	Feb. 28, 2023	Nov. 30, 2022	Aug. 31, 2022	May 31, 2022	Feb. 28, 2022	Nov. 30, 2021	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 35,422	$ 35,415	$ 34,862	$ 33,382	$ 32,449	$ 32,597	$ 33,756	$ 33,901	$ 139,081	$ 132,703	$ 132,509
Total long-lived assets	33,254				32,988				33,254	32,988
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									116,883	110,873	112,005
Total long-lived assets	28,951				28,710				28,951	28,710
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									8,984	8,894	8,298
Total long-lived assets	3,622				3,663				3,622	3,663
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									11,211	11,178	10,472
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									2,003	1,757	$ 1,734
Total long-lived assets	$ 681				$ 614				$ 681	$ 614