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Goodwill and other intangible assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2022	May 31, 2021	Aug. 31, 2021	Jun. 01, 2021
Goodwill [Line Items]
Goodwill	$ 21,901		$ 21,901		$ 12,421
Indefinite-lived intangible assets	6,695		6,695		7,342
Amortization of intangible assets	148	$ 156	488	$ 363
Minimum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						18.00%
Maximum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						195.00%
Other International Reporting Unit
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						29.00%
Goodwill	372		372		381
Boots Reporting Unit
Goodwill [Line Items]
Goodwill	956		956		1,100
Indefinite-lived intangible assets	$ 6,700		$ 6,700		$ 7,300
Boots Reporting Unit \| Minimum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						5.00%
Boots Reporting Unit \| Maximum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						27.00%