Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Supplemental information - Summary of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Feb. 28, 2021	Aug. 31, 2020	Feb. 29, 2020	Aug. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,030	$ 469
Cash, cash equivalents and restricted cash	1,311	746	$ 988	$ 1,207
Continuing Operations
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	1,030	469
Restricted cash	87	62
Discontinued Operations
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	68	47
Restricted cash	$ 126	$ 168