Equity method investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Millions	Nov. 30, 2020	Aug. 31, 2020
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 6,019	$ 7,338
AmerisourceBergen
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 4,030	$ 5,446
Ownership percentage	28.00%	28.00%
Others
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 1,989	$ 1,892
Others | Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	8.00%	8.00%
Others | Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%
Total
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 6,019	$ 7,338