Financial instruments - warrants (Details) - Derivatives not designated as hedges: - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Foreign currency forwards | Selling, general and administrative expense
Warrants [Abstract]
Gains (losses) due to changes in fair value of derivative instruments	$ (63)	$ 139	$ 17
Foreign currency forwards | Other income (expense)
Warrants [Abstract]
Gains (losses) due to changes in fair value of derivative instruments	11	(18)	22
Total return swap | Selling, general and administrative expense
Warrants [Abstract]
Gains (losses) due to changes in fair value of derivative instruments	$ 24	$ 0	$ 0