Equity method investments - summarized financial information of equity method investees (Details) - USD ($) $ in Millions	12 Months Ended
Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Equity Method Investment, Summarized Financial Information [Abstract]
Current assets	$ 34,493	$ 29,707
Non-current assets	14,971	12,999
Current liabilities	34,055	30,559
Non-current liabilities	8,759	7,362
Shareholders’ equity	6,650	4,785
Income Statement [Abstract]
Sales	179,887	164,844	$ 55,153
Gross profit	6,875	5,958	2,672
Net earnings	1,315	1,040	534
Share of earnings from equity method investments	$ 245	$ 143	$ 81

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