Accounting Policies Summary of Significant Accounting Policies (Schedule of Goodwill) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Jan. 31, 2015	Jan. 31, 2014
Goodwill [Roll Forward]
Goodwill	$ 19,510us-gaap_Goodwill	$ 20,497us-gaap_Goodwill
Changes in currency translation and other	(1,418)us-gaap_GoodwillTranslationAdjustments	(1,000)us-gaap_GoodwillTranslationAdjustments
Acquisitions(1)	10us-gaap_GoodwillAcquiredDuringPeriod	13us-gaap_GoodwillAcquiredDuringPeriod
Goodwill	18,102us-gaap_Goodwill	19,510us-gaap_Goodwill
Walmart International
Goodwill [Roll Forward]
Goodwill	18,746	19,741
Changes in currency translation and other	(1,418)	(1,000)
Acquisitions(1)	0	5
Goodwill	17,328	18,746
Sam's Club
Goodwill [Roll Forward]
Goodwill	313	313
Changes in currency translation and other	0	0
Acquisitions(1)	0	0
Goodwill	313	313
Walmart U.S.
Goodwill [Roll Forward]
Goodwill	451	443
Changes in currency translation and other	0	0
Acquisitions(1)	10	8
Goodwill	$ 461	$ 451

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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

- Details

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

- Definition

Amount of increase (decrease) from foreign currency translation adjustments 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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wmt_SamsClubMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wmt_WalmartInternationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=wmt_WalmartUSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: