Leases - additional information (Details)	12 Months Ended
Aug. 31, 2018 USD ($) lease	Aug. 31, 2017 USD ($)	Aug. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Total minimum lease payments	$ 32,736,000,000
Imputed interest and executory costs	813,000,000
Sublease rentals	331,000,000
Proceeds from sale leaseback transactions	0	$ 444,000,000	$ 60,000,000
Charges related to facilities that were closed or relocated	$ 129,000,000	$ 394,000,000	$ 127,000,000
Number of leases \| lease	16
Maximum
Operating Leased Assets [Line Items]
Potential undiscounted future payments	$ 22,000,000
Facility Closing
Operating Leased Assets [Line Items]
Total minimum lease payments	$ 1,600,000,000

Minimum payments receivable in the future under noncancelable subleases.

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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of cash inflow after closing and debt issuance costs received by a seller-lessee in a sale-leaseback recognized in investing activities.

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Charges related to facilities that were closed or relocated under long-term leases. These charges are reported in selling, general and administrative expenses.

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Amount of executory costs and imputed interest included in capital lease. Executory costs pertain to amount to be paid by lessee to lessor for maintenance, insurance, and tax expenses related to the leased asset. Imputed interest reduced the net minimum lease payments to present value calculated at the lesser of the interest rate implicit in the lease (if known) or the entity's incremental borrowing rate (as defined) at inception of the lease.

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The number of leases assigned where the entity has secondary liability.

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Maximum potential amount of future payments (undiscounted) the entity could be required to make under assigned lease.

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