Income taxes - provision for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Current provision
Federal	$ 759	$ 999	$ 846
State	45	56	121
Non–U.S.	390	371	128
Total current provisions for income taxes	1,194	1,426	1,095
Deferred provision
Federal	(306)	(183)	(23)
State	(24)	6	(16)
Non–U.S. – tax law change	(80)	(182)	0
Non–U.S. – excluding tax law change	(24)	(70)	0
Total non-current provisions for income taxes	(434)	(429)	(39)
Income tax provision	$ 760	$ 997	$ 1,056