Related parties (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Related Party Transactions [Abstract]
Purchases, net	$ 10,703	$ 10,632	$ 31,941	$ 31,436
Trade accounts payable, net	$ 4,148	$ 3,456	$ 4,148	$ 3,456