Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Asset Purchase Agreement, Number of Distribution Centers Acquired

+ References

No definition available.

+ Details

Name:	wba_AssetPurchaseAgreementNumberOfDistributionCentersAcquired
Namespace Prefix:	wba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Asset Purchase Agreement, Number of Distribution Centers Expected To Be Acquired

+ References

No definition available.

+ Details

Name:	wba_AssetPurchaseAgreementNumberofDistributionCentersExpectedToBeAcquired
Namespace Prefix:	wba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wba_RiteAidCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wba_RiteAidCorporationSecondAndThirdDistributionCenterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wba_RiteAidCorporationFirstDistributionCenterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wba_RetailPharmacyUSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Acquisitions (Details) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Acquisitions (Details) $ in Millions	May 31, 2020 USD ($) distribution_center	May 31, 2020 USD ($) distribution_center	Aug. 31, 2019 USD ($) distribution_center
Rite Aid Corporation
Business Acquisition [Line Items]
Payments to acquire business	$ 28
Number of distribution centers acquired \| distribution_center			1
Number of distribution centers expected to be acquired \| distribution_center	3	3
Rite Aid Corporation - Second and Third Distribution Center
Business Acquisition [Line Items]
Payments to acquire business		$ 91
Number of distribution centers acquired \| distribution_center	2	2
Rite Aid Corporation - First Distribution Center
Business Acquisition [Line Items]
Payments to acquire business			$ 61
Retail Pharmacy USA
Business Acquisition [Line Items]
Payments to acquire business	$ 27	$ 166