Goodwill and other intangible assets - Schedule of Goodwill (Details) $ in Millions	6 Months Ended
Feb. 28, 2019 USD ($)
Goodwill [Roll Forward]
Net book value - Beginning Period	$ 16,914
Acquisitions	8
Disposals	(8)
Currency translation adjustments	113
Net book value - Ending Period	17,027
Retail Pharmacy USA
Goodwill [Roll Forward]
Net book value - Beginning Period	10,483
Acquisitions	8
Disposals	0
Currency translation adjustments	0
Net book value - Ending Period	10,491
Retail Pharmacy International
Goodwill [Roll Forward]
Net book value - Beginning Period	3,370
Acquisitions	0
Disposals	(8)
Currency translation adjustments	59
Net book value - Ending Period	3,421
Pharmaceutical Wholesale
Goodwill [Roll Forward]
Net book value - Beginning Period	3,061
Acquisitions	0
Disposals	0
Currency translation adjustments	54
Net book value - Ending Period	$ 3,115

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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-Publisher FASB
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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

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Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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