Segments and Disaggregated Revenue (Revenue, International) (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 30, 2020	Apr. 30, 2019
Revenue from External Customer [Line Items]
Net sales	$ 133,672	$ 122,949
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,766	28,775
Mexico and Central America \| Walmart International
Revenue from External Customer [Line Items]
Net sales	8,496	7,837
United Kingdom \| Walmart International
Revenue from External Customer [Line Items]
Net sales	7,132	7,077
Canada \| Walmart International
Revenue from External Customer [Line Items]
Net sales	4,286	4,122
China \| Walmart International
Revenue from External Customer [Line Items]
Net sales	3,368	3,063
Other \| Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 6,484	$ 6,676

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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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