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Goodwill and other intangible assets - narrative (Details) $ in Millions	12 Months Ended
	Aug. 31, 2022 USD ($)	Aug. 31, 2021 USD ($)	Aug. 31, 2020 USD ($) reportingUnit	Jun. 01, 2022	Jun. 01, 2021
Goodwill [Line Items]
Goodwill	$ 22,280	$ 12,421	$ 12,013
Indefinite lived intangible assets	5,528	7,342
Number of reporting segments included in impairment analysis \| reportingUnit			2
Impairment of definite-lived intangible assets	0	0	$ 47
Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration]			Selling, general and administrative expenses
Amortization expense for intangible assets	639	523	$ 384
Minimum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount				7.00%	7.00%
Maximum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount				198.00%	18.00%
Pharmacy licenses
Goodwill [Line Items]
Indefinite lived intangible assets	1,209	2,066
Boots Reporting Unit
Goodwill [Line Items]
Goodwill	906
Impairment of intangible assets	783	49	294
Indefinite lived intangible assets	$ 5,500	$ 7,300
Goodwill impairment loss			$ 1,700