Goodwill and other intangible assets - Schedule of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	May 31, 2024	Feb. 29, 2024	May 31, 2023	May 31, 2024	May 31, 2023
Goodwill [Roll Forward]
Goodwill, beginning balance				$ 28,187
Adjustments				19
Impairments	$ 0		$ 0	(12,369)	$ 0
Cumulative translation adjustments and other				(16)
Goodwill, ending balance	15,821			15,821
International
Goodwill [Roll Forward]
Impairments	(431)
U.S. Healthcare
Goodwill [Roll Forward]
Impairments		$ (12,400)
Reportable Segments | U.S. Retail Pharmacy
Goodwill [Roll Forward]
Goodwill, beginning balance				10,947
Adjustments				0
Impairments				0
Cumulative translation adjustments and other				0
Goodwill, ending balance	10,947			10,947
Reportable Segments | International
Goodwill [Roll Forward]
Goodwill, beginning balance				1,378
Adjustments				0
Impairments				0
Cumulative translation adjustments and other				(8)
Goodwill, ending balance	1,370			1,370
Reportable Segments | U.S. Healthcare
Goodwill [Roll Forward]
Goodwill, beginning balance				15,863
Adjustments				19
Impairments				(12,369)
Cumulative translation adjustments and other				(8)
Goodwill, ending balance	$ 3,505			$ 3,505