Equity method investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Millions	Feb. 28, 2021	Aug. 31, 2020
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 6,202	$ 7,204
AmerisourceBergen
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 4,121	$ 5,446
Ownership percentage	28.00%	28.00%
Others
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investments	$ 2,081	$ 1,758
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	$ 6,202	$ 7,204