Exit and disposal activities - Restructuring Costs (Details) - Transformational Cost Management Program - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2021	Nov. 30, 2020
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	$ 175	$ 81
Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	123	48
Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	44	21
Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	9	12
Lease obligations and other real estate costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	89	22
Lease obligations and other real estate costs | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	87	22
Lease obligations and other real estate costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	2	0
Lease obligations and other real estate costs | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	0	0
Asset impairments
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	40	1
Asset impairments | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	15	4
Asset impairments | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	25	(2)
Asset impairments | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	0	0
Employee severance and business transition costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	37	52
Employee severance and business transition costs | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	20	12
Employee severance and business transition costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	10	28
Employee severance and business transition costs | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	7	12
Information technology transformation and other exit costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	9	5
Information technology transformation and other exit costs | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	1	10
Information technology transformation and other exit costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	7	(5)
Information technology transformation and other exit costs | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	$ 1	$ 0