Income taxes - components of earnings before income tax provision (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Income Tax Disclosure [Abstract]
U.S.	$ 759	$ 1,898	$ 3,292
Non–U.S.	(16)	2,629	2,683
Earnings before income tax provision	$ 743	$ 4,527	$ 5,975