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Goodwill and other intangible assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2021	May 31, 2020	Aug. 31, 2020	Jun. 01, 2020
Goodwill [Line Items]
Goodwill	$ 12,493		$ 12,493		$ 12,013
Indefinite-lived intangible assets	7,675		7,675		$ 7,231
Amortization of intangible assets	156	$ 94	363	$ 290
Minimum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						4.00%
Maximum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						239.00%
Other International Reporting Unit
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						4.00%
Goodwill	400		400
Boots Reporting Unit
Goodwill [Line Items]
Goodwill	1,100		1,100
Indefinite-lived intangible assets	$ 7,700		$ 7,700
Boots Reporting Unit \| Minimum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						4.00%
Boots Reporting Unit \| Maximum
Goodwill [Line Items]
Reporting unit fair value in excess of carrying amount (as a percent)						31.00%