Exit and disposal activities - Restructuring Costs (Details) - Transformational Cost Management Program - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	$ 56	$ 154	$ 231	$ 235
Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	43	122	166	170
Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	8	16	51	36
Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	5	17	14	29
Lease obligations and other real estate costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	5	18	95	40
Lease obligations and other real estate costs | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	5	18	91	40
Lease obligations and other real estate costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	1	0	3	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	0	0
Asset impairments
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	4	4	44	5
Asset impairments | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	1	1	16	5
Asset impairments | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	3	3	28	0
Asset impairments | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	0	0	0	0
Employee severance and business transition costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	41	122	79	174
Employee severance and business transition costs | Reportable segments | United States
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	36	99	56	111
Employee severance and business transition costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	0	6	9	34
Employee severance and business transition costs | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	5	17	14	29
Information technology transformation and other exit costs
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	5	11	13	15
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	4	2	14
Information technology transformation and other exit costs | Reportable segments | International
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	4	7	11	2
Information technology transformation and other exit costs | Corporate and Other
Restructuring Cost and Reserve [Line Items]
Total pre-tax exit and disposal charges	$ 0	$ 0	$ 0	$ 0