Goodwill and other intangible assets - Schedule of Goodwill (Details) $ in Millions	3 Months Ended
Nov. 30, 2022 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 22,280
Acquisitions	25
Adjustments	258
Currency translation adjustments	19
Goodwill, ending balance	22,582
Reportable Segments \| U.S. Retail Pharmacy
Goodwill [Roll Forward]
Goodwill, beginning balance	10,947
Acquisitions	0
Adjustments	0
Currency translation adjustments	0
Goodwill, ending balance	10,947
Reportable Segments \| International
Goodwill [Roll Forward]
Goodwill, beginning balance	1,293
Acquisitions	0
Adjustments	0
Currency translation adjustments	19
Goodwill, ending balance	1,312
Reportable Segments \| U.S. Healthcare
Goodwill [Roll Forward]
Goodwill, beginning balance	10,040
Acquisitions	25
Adjustments	258
Currency translation adjustments	0
Goodwill, ending balance	$ 10,323

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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