Goodwill and other intangible assets - schedule of goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2023	Aug. 31, 2022
Goodwill [Roll Forward]
Beginning balance	$ 22,280	$ 12,421
Acquisitions	5,588	10,040
Goodwill, purchase accounting adjustments	252
Currency translation adjustments and other	67	(181)
Ending balance	28,187	22,280
VillageMD
Goodwill [Roll Forward]
Acquisitions		8,000
Goodwill, purchase accounting adjustments	125
Shields Health Solutions
Goodwill [Roll Forward]
Acquisitions		1,500
Goodwill, purchase accounting adjustments	72
CareCentrix, Inc.
Goodwill [Roll Forward]
Beginning balance	509
Acquisitions		454
Goodwill, purchase accounting adjustments	56
Ending balance		509
Reportable Segments | U.S. Retail Pharmacy
Goodwill [Roll Forward]
Beginning balance	10,947	10,947
Acquisitions	0	0
Goodwill, purchase accounting adjustments	0
Currency translation adjustments and other	0	0
Ending balance	10,947	10,947
Reportable Segments | International
Goodwill [Roll Forward]
Beginning balance	1,293	1,474
Acquisitions	0	0
Goodwill, purchase accounting adjustments	0
Currency translation adjustments and other	85	(181)
Ending balance	1,378	1,293
Reportable Segments | U.S. Healthcare
Goodwill [Roll Forward]
Beginning balance	10,040	0
Acquisitions	5,588	10,040
Goodwill, purchase accounting adjustments	252
Currency translation adjustments and other	(18)	0
Ending balance	$ 15,863	$ 10,040