Equity method investments - Summarized Financial Information of Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2020	Nov. 30, 2019
Income Statement [Abstract]
Sales	$ 36,307	$ 34,339
Gross profit	7,139	7,263
Net earnings (loss)	(299)	842
Share of earnings (loss) from equity method investments	(1,350)	4
Equity Method Investment
Income Statement [Abstract]
Sales	56,548	51,581
Gross profit	2,472	7,733
Net earnings (loss)	$ (4,798)	$ 1,528