Income taxes - unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Reconciliation of Unrecognized Tax Benefits
Balance at beginning of year	$ 456	$ 409	$ 269
Gross increases related to tax positions in a prior period	33	123	151
Gross decreases related to tax positions in a prior period	(53)	(15)	(36)
Gross increases related to tax positions in the current period	26	29	33
Settlements with taxing authorities	(2)	(87)	(2)
Currency	0	0	(1)
Lapse of statute of limitations	(5)	(3)	(5)
Balance at end of year	$ 455	$ 456	$ 409

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

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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