Equity method investments - summarized financial information of equity method investees (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Statement of Financial Position [Abstract]
Current assets	$ 18,073				$ 18,700				$ 18,073	$ 18,700
Non-current assets	69,101				48,899				69,101	48,899
Current liabilities	27,070				25,769				27,070	25,769
Non-current liabilities	38,968				17,678				38,968	17,678
Shareholders' equity	21,136				24,152				21,136	24,152	$ 26,689	$ 28,274
Noncontrolling interests	498				641				498	641
Income Statement [Abstract]
Sales	34,746	$ 34,631	$ 35,820	$ 34,339	33,954	$ 34,591	$ 34,528	$ 33,793	139,537	136,866	131,537
Gross profit	6,803	$ 6,438	$ 7,513	$ 7,263	7,228	$ 7,453	$ 7,754	$ 7,641	28,017	30,076	30,792
Net earnings									424	3,962	5,031
Share of earnings from equity method investments									382	187	245
Equity Method Investment
Statement of Financial Position [Abstract]
Current assets	40,038				36,523				40,038	36,523
Non-current assets	18,313				15,710				18,313	15,710
Current liabilities	38,779				35,857				38,779	35,857
Non-current liabilities	10,628				9,633				10,628	9,633
Shareholders' equity	8,944				6,743				8,944	6,743
Noncontrolling interests	$ 387				$ 411				387	411
Income Statement [Abstract]
Sales									210,306	197,237	179,887
Gross profit									8,896	7,516	6,875
Net earnings									$ 1,647	$ 1,037	$ 1,315