Segments and Disaggregated Revenue - Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 30, 2020	Apr. 30, 2019
Segment Reporting Information [Line Items]
Net sales	$ 133,672	$ 122,949
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	88,743	80,344
Walmart International
Segment Reporting Information [Line Items]
Net sales	29,766	28,775
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 15,163	$ 13,830

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

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