Segment reporting - geographic data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Aug. 31, 2022	May 31, 2022	Feb. 28, 2022	Nov. 30, 2021	Aug. 31, 2021	May 31, 2021	Feb. 28, 2021	Nov. 30, 2020	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 32,449	$ 32,597	$ 33,756	$ 33,901	$ 34,262	$ 34,030	$ 32,779	$ 31,438	$ 132,703	$ 132,509	$ 121,982
Total long-lived assets	11,729				12,247				11,729	12,247
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									110,873	112,005	107,701
Total long-lived assets	9,577				9,665				9,577	9,665
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									8,894	8,298	7,830
Total long-lived assets	1,838				2,205				1,838	2,205
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									11,178	10,472	4,876
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									1,757	1,734	$ 1,575
Total long-lived assets	$ 314				$ 377				$ 314	$ 377