Segments and Disaggregated Revenue Revenue from Contract with Customer Excluding Assessed Tax, International (Details) - Walmart International $ in Millions	3 Months Ended
Apr. 30, 2018 USD ($)
Mexico and Central America [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 7,684
United Kingdom
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	7,515
Canada [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	4,254
China [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	3,205
Other [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	7,602
Geographical, Total [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 30,260

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 32
-Paragraph 2A
-URI http://asc.fasb.org/extlink&oid=82859839&loc=SL82860478-203043

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130543-203045

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130539-203045

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130545-203045

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