Operating Income by Segment, Interest, Net, and Unrealized (Gains) and Losses (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Segment Reporting Information [Line Items]
Operating income	$ 4,718	$ 4,986	$ 15,246	$ 15,890
Interest, net	589	534	1,799	1,524
Other (gains) and losses	(244)	1,876	(996)	8,570
Income before income taxes	4,373	2,576	14,443	5,796
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income	4,176	3,937	12,977	12,343
Walmart International
Segment Reporting Information [Line Items]
Operating income	634	1,179	2,265	3,713
Sam's Club
Segment Reporting Information [Line Items]
Operating income	327	379	1,258	1,106
Corporate and support
Segment Reporting Information [Line Items]
Operating income	$ (419)	$ (509)	$ (1,254)	$ (1,272)

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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-Name Accounting Standards Codification
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-SubTopic 220
-Section S99
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-Topic 220
-SubTopic 10
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The net result for the period of deducting operating expenses from operating revenues.

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