Segments and Disaggregated Revenue (Operating Income by Segment, Interest, Net, and Unrealized (Gains) and Losses) (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]
Operating income	$ 6,059	$ 5,583	$ 11,283	$ 10,528
Interest, net	635	585	1,184	1,210
Other (gains) and losses	(3,222)	85	(3,943)	(752)
Income before income taxes	8,646	4,913	14,042	10,070
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income	5,057	4,659	9,359	8,801
Walmart International
Segment Reporting Information [Line Items]
Operating income	812	893	1,618	1,631
Sam's Club
Segment Reporting Information [Line Items]
Operating income	592	480	1,086	931
Corporate and support
Segment Reporting Information [Line Items]
Operating income	$ (402)	$ (449)	$ (780)	$ (835)

Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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The net amount of operating interest income (expense).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7)
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The net result for the period of deducting operating expenses from operating revenues.

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