Percentage of principal amount of debt redeemed.

No definition available.

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- Definition

Amount of cash paid for interest. Includes, but is not limited to, payment to settle zero-coupon bond attributable to accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

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Balance Type:	credit
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611

+ Details

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Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Redemption Price, Accrued and Unpaid Interest

+ References

No definition available.

+ Details

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Namespace Prefix:	wba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of Tranches

+ References

No definition available.

+ Details

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Namespace Prefix:	wba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wba_March2018RevolvingCreditFacilityMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wba_August2017RevolvingCreditAgreementMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=us-gaap_LoansPayableMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wba_February2017RevolvingCreditAgreementMember
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Data Type:	na
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- Details

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Debt - Loan Agreements and Other Borrowings (Details)			9 Months Ended
Debt - Loan Agreements and Other Borrowings (Details)	Jun. 05, 2017 USD ($)	Jun. 01, 2016 USD ($) tranche	May 31, 2018 USD ($)	May 31, 2017 USD ($)	Mar. 14, 2018 USD ($)	Aug. 24, 2017 USD ($)
Line of Credit Facility [Line Items]
Proceeds from notes payable		$ 6,000,000,000
Number of tranches \| tranche		5
Redemption price, percentage of principal amount redeemed	101.00%
Redemption price, accrued and unpaid interest	$ 1,000,000
Interest paid			$ 450,000,000	$ 573,000,000
Revolving Credit Facility \| March 2018 Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 350,000,000
Revolving Credit Facility \| August 2017 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Borrowing outstanding			$ 0
Commercial paper
Line of Credit Facility [Line Items]
Average daily short-term borrowings				$ 1,400,000,000
Weighted-average interest rate				2.00%
Term Loan \| Maximum
Line of Credit Facility [Line Items]
Debt to total capitalization ratio			0.60
Medium-term Notes \| August 2017 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 1,000,000,000.0
Medium-term Notes \| February 2017 Revolving Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						1,000,000,000.0
Borrowing outstanding			$ 0
Medium-term Notes \| 2017 Term Loan Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity						$ 1,000,000,000.0
Borrowing outstanding			$ 1,000,000,000