Related parties (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018	Aug. 31, 2018
Related Party Transactions [Abstract]
Purchases, net	$ 14,064	$ 12,132	$ 28,386	$ 23,736
Trade accounts payable, net	$ 6,511		$ 6,511		$ 6,274

Amount for accounts payable to related parties.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant