Goodwill and other intangible assets - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2025 USD ($)	Feb. 29, 2024 USD ($) clinic	Feb. 28, 2025 USD ($)	Feb. 29, 2024 USD ($) clinic
Goodwill [Line Items]
Impairment of goodwill	$ 3,653	$ 12,369	$ 3,653	$ 12,369
Impairment		$ 266
Impairment of goodwill, intangibles and long-lived assets			$ 5,660	$ 13,589
U.S. Healthcare
Goodwill [Line Items]
Impairment of goodwill	178
U.S. Retail Pharmacy
Goodwill [Line Items]
Impairment of goodwill	2,000
Transformational Cost Management Program
Goodwill [Line Items]
Number of clinics closed | clinic		90		160
VillageMD
Goodwill [Line Items]
Impairment of goodwill	1,500	$ 12,400
Impairment	1,600
Impairment of goodwill, intangibles and long-lived assets	3,000
Asset impairment charges, net of controlling interest	1,900
U.S. Retail Pharmacy, CareCentrix, and Boots
Goodwill [Line Items]
Impairment of goodwill, intangibles and long-lived assets	2,300
Boots | International
Goodwill [Line Items]
Impairment of intangible assets (excluding goodwill)	$ 115