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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.

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Acquisitions - narrative (Details) $ in Millions			12 Months Ended
Acquisitions - narrative (Details) $ in Millions	Sep. 19, 2017 USD ($) distribution_center store	Mar. 31, 2017 USD ($)	Aug. 31, 2019 USD ($) distribution_center	Aug. 31, 2018 USD ($) store	Aug. 31, 2017 USD ($)
Business Acquisition [Line Items]
Consideration			$ 304
Goodwill			$ 16,560	$ 16,914	$ 15,632
Rite Aid
Business Acquisition [Line Items]
Number of stores expected to be acquired \| store	1,932
Number of distribution centers expected to be acquired \| distribution_center	3		2
Consideration to be transferred	$ 4,375
Number of stores acquired \| store				1,932
Consideration				$ 4,157
Goodwill			$ 1,331
Total consideration			4,330	$ 4,300
Rite Aid Corporation - First Distribution Center
Business Acquisition [Line Items]
Payments to acquire business			$ 61
AllianceRx Walgreens Prime
Business Acquisition [Line Items]
Goodwill		$ 103
Total consideration		$ 720
Customer Contracts \| AllianceRx Walgreens Prime
Business Acquisition [Line Items]
Weighted average useful life		15 years