Goodwill and other intangible assets - narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
	Aug. 31, 2024 USD ($)	Feb. 29, 2024 USD ($) clinic	Aug. 31, 2024 USD ($)	Aug. 31, 2023 USD ($)	Aug. 31, 2022 USD ($)	Jun. 01, 2024
Goodwill [Line Items]
Impairment of goodwill			$ 12,701	$ 0	$ 0
Goodwill	$ 15,506		15,506	$ 28,187	22,280
Impairment, Intangible Asset, Statement of Income or Comprehensive Income [Extensible Enumeration]				Selling, general and administrative expenses
Indefinite lived intangible assets	5,607		5,607	$ 5,477
Impairment of definite-lived intangible assets				0	0
Amortization expense for intangible assets			963	815	639
U.S. Healthcare
Goodwill [Line Items]
Impairment of goodwill, intangibles and long-lived assets		$ 266
International
Goodwill [Line Items]
Impairment of goodwill					1,700
Transformational cost management program
Goodwill [Line Items]
Number of clinics closed | clinic		90
Minimum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount						18.00%
Maximum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount						124.00%
Pharmacy licenses
Goodwill [Line Items]
Indefinite lived intangible assets	848		848	828
VillageMD
Goodwill [Line Items]
Impairment of goodwill		$ 12,400
Goodwill	1,500		1,500
CareCentrix, Inc.
Goodwill [Line Items]
Impairment of goodwill	332
Goodwill	178		178
Boots Reporting Unit
Goodwill [Line Items]
Impairment of intangible assets				431	$ 783
Indefinite lived intangible assets	$ 5,600		$ 5,600	$ 5,500
Boots Reporting Unit | Minimum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount	6.00%		6.00%
Boots Reporting Unit | Maximum
Goodwill [Line Items]
Percentage of reporting unit fair value in excess of carrying amount	73.00%		73.00%