Goodwill and other intangible assets - schedule of finite-lived intangible assets by major class (Details) - USD ($) $ in Millions	Aug. 31, 2022	Aug. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	$ 7,155	$ 4,421
Total accumulated amortization	1,953	1,826
Total amortizable intangible assets, net	5,202	2,595
Total indefinite-lived intangible assets	5,528	7,342
Total intangible assets, net	10,730	9,936
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Total indefinite-lived intangible assets	4,319	5,276
Pharmacy licenses
Finite-Lived Intangible Assets [Line Items]
Total indefinite-lived intangible assets	1,209	2,066
Customer relationships and loyalty card holders
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	4,619	3,522
Total accumulated amortization	1,548	1,335
Primary Care Provider Network
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	1,247	0
Total accumulated amortization	64	0
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	760	361
Total accumulated amortization	246	226
Developed Technology Rights
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	436	156
Total accumulated amortization	56	8
Purchasing and payor contracts
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	15	317
Total accumulated amortization	4	227
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Total gross amortizable intangible assets	78	65
Total accumulated amortization	$ 35	$ 29