Segments and Disaggregated Revenue - Net Sales (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 136,824	$ 129,388	$ 270,496	$ 252,337
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	93,282	85,200	182,025	165,544
Walmart International
Segment Reporting Information [Line Items]
Net sales	27,167	29,139	56,933	57,914
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 16,375	$ 15,049	$ 31,538	$ 28,879

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