Fair value measurements (Details) - USD ($) $ in Millions	Aug. 31, 2020	Aug. 31, 2019
Liabilities [Abstract]
Carrying value of long-term notes outstanding	$ 15,816
Recurring
Assets [Abstract]
Money market funds	6	$ 217
Investment in equity securities	1	5
Recurring \| Foreign currency forwards
Assets [Abstract]
Derivative asset	20	88
Liabilities [Abstract]
Derivative liability	80	6
Recurring \| Cross currency interest rate swaps
Assets [Abstract]
Derivative asset	16	73
Liabilities [Abstract]
Derivative liability	16
Recurring \| Interest rate swaps
Liabilities [Abstract]
Derivative liability	10
Recurring \| Total return swap
Liabilities [Abstract]
Derivative liability	1
Recurring \| Level 1
Assets [Abstract]
Money market funds	6	217
Investment in equity securities	1	5
Recurring \| Level 1 \| Foreign currency forwards
Assets [Abstract]
Derivative asset	0	0
Liabilities [Abstract]
Derivative liability	0	0
Recurring \| Level 1 \| Cross currency interest rate swaps
Assets [Abstract]
Derivative asset	0	0
Liabilities [Abstract]
Derivative liability	0
Recurring \| Level 1 \| Interest rate swaps
Liabilities [Abstract]
Derivative liability	0
Recurring \| Level 1 \| Total return swap
Liabilities [Abstract]
Derivative liability	0
Recurring \| Level 2
Assets [Abstract]
Money market funds	0	0
Investment in equity securities	0	0
Recurring \| Level 2 \| Foreign currency forwards
Assets [Abstract]
Derivative asset	20	88
Liabilities [Abstract]
Derivative liability	80	6
Recurring \| Level 2 \| Cross currency interest rate swaps
Assets [Abstract]
Derivative asset	16	73
Liabilities [Abstract]
Derivative liability	16
Recurring \| Level 2 \| Interest rate swaps
Liabilities [Abstract]
Derivative liability	10
Recurring \| Level 2 \| Total return swap
Liabilities [Abstract]
Derivative liability	1
Recurring \| Level 3
Assets [Abstract]
Money market funds	0	0
Investment in equity securities	0	0
Recurring \| Level 3 \| Foreign currency forwards
Assets [Abstract]
Derivative asset	0	0
Liabilities [Abstract]
Derivative liability	0	0
Recurring \| Level 3 \| Cross currency interest rate swaps
Assets [Abstract]
Derivative asset	0	$ 0
Liabilities [Abstract]
Derivative liability	0
Recurring \| Level 3 \| Interest rate swaps
Liabilities [Abstract]
Derivative liability	0
Recurring \| Level 3 \| Total return swap
Liabilities [Abstract]
Derivative liability	0
Carrying Value
Liabilities [Abstract]
Carrying value of long-term notes outstanding	12,700
Estimate of Fair Value Measurement
Liabilities [Abstract]
Fair value of long-term notes outstanding	$ 13,700

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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