Operating Income by Segment, Interest, Net, and Unrealized (Gains) and Losses (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 30, 2019	Apr. 30, 2018
Segment Reporting Information [Line Items]
Operating income	$ 4,945	$ 5,154
Interest, net	625	487
Other (gains) and losses	(837)	1,845
Income before income taxes	5,157	2,822
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income	4,142	3,927
Walmart International
Segment Reporting Information [Line Items]
Operating income	738	1,265
Sam's Club
Segment Reporting Information [Line Items]
Operating income	451	325
Corporate and support
Segment Reporting Information [Line Items]
Operating income	$ (386)	$ (363)

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).

+ References

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

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