Goodwill and other intangible assets - Schedule of Finite-Lived Intangible Assets by Major Class (Details) - USD ($) $ in Millions	May 31, 2023	Aug. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	$ 10,563	$ 7,155
Accumulated amortization	2,371	1,953
Total amortizable intangible assets, net	8,191	5,202
Indefinite-lived intangible assets	5,387	5,528
Total intangible assets, net	13,578	10,730
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	4,544	4,319
Pharmacy licenses
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	843	1,209
Customer relationships and loyalty card holders
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	4,490	4,619
Accumulated amortization	1,673	1,548
Provider networks
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	3,217	1,247
Accumulated amortization	180	64
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	2,290	760
Accumulated amortization	351	246
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	469	436
Accumulated amortization	123	56
Others
Finite-Lived Intangible Assets [Line Items]
Gross amortizable intangible assets	97	93
Accumulated amortization	$ 44	$ 39