Goodwill and other intangible assets - Schedule of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	May 31, 2025	Feb. 28, 2025	May 31, 2024	May 31, 2025	May 31, 2024	Aug. 31, 2024
Goodwill [Roll Forward]
Goodwill, beginning balance				$ 15,506
Impairments	$ 0		$ 0	(3,653)	$ (12,369)
Cumulative translation adjustments				28
Goodwill, ending balance	11,882			11,882
U.S. Retail Pharmacy
Goodwill [Roll Forward]
Impairments		$ (2,000)
U.S. Healthcare
Goodwill [Roll Forward]
Impairments		$ (178)
Reportable Segments | U.S. Retail Pharmacy
Goodwill [Roll Forward]
Goodwill, beginning balance				10,947
Impairments				(2,008)
Cumulative translation adjustments				0
Goodwill, ending balance	8,938			8,938
Goodwill, impaired, accumulated impairment loss						$ 0
Reportable Segments | International
Goodwill [Roll Forward]
Goodwill, beginning balance				1,388
Impairments				0
Cumulative translation adjustments				28
Goodwill, ending balance	1,415			1,415
Goodwill, impaired, accumulated impairment loss						1,700
Reportable Segments | U.S. Healthcare
Goodwill [Roll Forward]
Goodwill, beginning balance				3,173
Impairments				(1,645)
Cumulative translation adjustments				0
Goodwill, ending balance	$ 1,528			$ 1,528
Goodwill, impaired, accumulated impairment loss						$ 12,700