Exit and disposal activities - restructuring reserve activity (Details) $ in Millions	3 Months Ended
	Nov. 30, 2018 USD ($)
Store Optimization Program
Restructuring Reserve [Roll Forward]
August 31, 2018	$ 329
Costs	20
Payments	(81)
Other - non cash	87
November 30, 2018	355
Cost Transformation restructuring Program
Restructuring Reserve [Roll Forward]
August 31, 2018	421
Payments	(22)
Other - non cash	5
Currency translation adjustments	1
November 30, 2018	405
Lease obligations and other real estate costs | Store Optimization Program
Restructuring Reserve [Roll Forward]
August 31, 2018	308
Costs	(7)
Payments	(47)
Other - non cash	86
November 30, 2018	340
Employee severance and other exit costs | Store Optimization Program
Restructuring Reserve [Roll Forward]
August 31, 2018	21
Costs	27
Payments	(34)
Other - non cash	1
November 30, 2018	15
Employee severance and other exit costs | Cost Transformation restructuring Program
Restructuring Reserve [Roll Forward]
August 31, 2018	7
Payments	(1)
Other - non cash	0
Currency translation adjustments	1
November 30, 2018	7
Real estate costs | Cost Transformation restructuring Program
Restructuring Reserve [Roll Forward]
August 31, 2018	414
Payments	(21)
Other - non cash	5
Currency translation adjustments	0
November 30, 2018	$ 398