Income taxes - unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Reconciliation of Unrecognized Tax Benefits
Balance at beginning of year	$ 269	$ 261	$ 193
Gross increases related to business combination	0	0	84
Gross increases related to tax positions in a prior period	151	21	45
Gross decreases related to tax positions in a prior period	(36)	(47)	(75)
Gross increases related to tax positions in the current period	33	68	63
Settlements with taxing authorities	(2)	(17)	(45)
Currency	(1)	(11)	0
Lapse of statute of limitations	(5)	(6)	(4)
Balance at end of year	$ 409	$ 269	$ 261

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

+ Details

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- Definition

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

+ References

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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

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- Definition

Amount of increase in unrecognized tax benefits resulting from acquisitions.

+ References

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- Definition

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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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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- Definition

Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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