Exit and disposal activities - restructuring reserve (Details) $ in Millions	12 Months Ended
	Aug. 31, 2017 USD ($)
Restructuring Reserve [Roll Forward]
August 31, 2016	$ 275
Restructuring costs	835
Payments	(218)
Other - non cash	(295)
Currency translation adjustments	3
August 31, 2017	600
Asset impairments
Restructuring Reserve [Roll Forward]
August 31, 2016	0
Restructuring costs	295
Payments	0
Other - non cash	(295)
Currency translation adjustments	0
August 31, 2017	0
Real estate costs
Restructuring Reserve [Roll Forward]
August 31, 2016	248
Restructuring costs	372
Payments	(99)
Other - non cash	0
Currency translation adjustments	0
August 31, 2017	521
Severance and other business transition and exit costs
Restructuring Reserve [Roll Forward]
August 31, 2016	27
Restructuring costs	168
Payments	(119)
Other - non cash	0
Currency translation adjustments	3
August 31, 2017	$ 79