Depreciation and Amortization (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Nov. 30, 2014	Nov. 30, 2013
Depreciation and Amortization [Abstract]
Depreciation expense	$ 235us-gaap_Depreciation	$ 235us-gaap_Depreciation
Amortization expense	63us-gaap_AmortizationOfDeferredCharges	70us-gaap_AmortizationOfDeferredCharges
System development costs amortization	21	27
Total depreciation and amortization expense	319	332
Amortization expense attributable to Alliance Boots	22	21
Amortization attributable to assets of equity method investment	8	8
Amortization expense attributable to Alliance Boots, operations	$ 14	$ 13

The amount of amortization of deferred charges applied against earnings during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

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

- Details

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

+ Details

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

- Definition

The aggregate expense charged against earnings which is attributable to the equity method investment.

+ References

No definition available.

+ Details

Name:	wag_AmortizationAttributableToEquityMethodInvestment
Namespace Prefix:	wag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate expense charged against earnings which is attributable to the assets of equity method investment.

+ References

No definition available.

+ Details

Name:	wag_AmortizationAttributableToEquityMethodInvestmentAssets
Namespace Prefix:	wag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate expense charged against earnings which is attributable to the operations income (loss) of equity method investment.

+ References

No definition available.

+ Details

Name:	wag_AmortizationAttributableToEquityMethodInvestmentOperations
Namespace Prefix:	wag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

For each income statement presented, the amount charged to expense for amortization of internally developed software costs.

+ References

No definition available.

+ Details

Name:	wag_InternallyDevelopedSoftwareAmortization
Namespace Prefix:	wag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration