Exit and disposal activities - restructuring reserve activity (Details) - USD ($) $ in Millions	12 Months Ended
Aug. 31, 2020	Aug. 31, 2019
Transformational cost management program
Restructuring Reserve [Roll Forward]
Beginning balance	$ 78	$ 0
Costs	720	432
Payments	(286)	(90)
Other - non cash	(255)	(265)
ASC 842 leases adoption	(4)
Currency	5	1
Ending balance	257	78
Transformational cost management program \| Lease obligations and other real estate costs
Restructuring Reserve [Roll Forward]
Beginning balance	17	0
Costs	217	25
Payments	(43)	(8)
Other - non cash	(166)	0
ASC 842 leases adoption	(4)
Currency	1	0
Ending balance	22	17
Transformational cost management program \| Asset impairments
Restructuring Reserve [Roll Forward]
Beginning balance	0	0
Costs	90	260
Payments	0	0
Other - non cash	(90)	(260)
ASC 842 leases adoption	0
Currency	0	0
Ending balance	0	0
Transformational cost management program \| Employee severance and business transition costs
Restructuring Reserve [Roll Forward]
Beginning balance	57	0
Costs	295	125
Payments	(142)	(69)
Other - non cash	13	0
ASC 842 leases adoption	0
Currency	4	1
Ending balance	227	57
Transformational cost management program \| Information technology transformation and other exit costs
Restructuring Reserve [Roll Forward]
Beginning balance	4	0
Costs	118	22
Payments	(102)	(13)
Other - non cash	(11)	(6)
ASC 842 leases adoption	0
Currency	0	0
Ending balance	8	4
Store optimization program
Restructuring Reserve [Roll Forward]
Beginning balance	429	329
Costs	53	196
Payments	(76)	(240)
Other - non cash	(23)	144
ASC 842 leases adoption	(378)
Ending balance	6	429
Store optimization program \| Lease obligations and other real estate costs
Restructuring Reserve [Roll Forward]
Beginning balance	407	308
Costs	22	119
Payments	(36)	(171)
Other - non cash	(11)	152
ASC 842 leases adoption	(378)
Ending balance	5	407
Store optimization program \| Employee severance and other exit costs
Restructuring Reserve [Roll Forward]
Beginning balance	22	21
Costs	31	77
Payments	(40)	(69)
Other - non cash	(12)	(7)
ASC 842 leases adoption	0
Ending balance	$ 1	$ 22

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 17
-Subparagraph (f)
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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of foreign currency translation gain (loss) which decreases (increases) the restructuring reserve.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
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Restructuring Reserve, Accounting Pronouncement Adjustments

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Restructuring Reserve, Other, Non-Cash

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