Operating Income by Segment, Interest, Net, and Unrealized (Gains) and Losses (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 30, 2018	Apr. 30, 2017
Segment Reporting Information [Line Items]
Operating income (loss):	$ 5,154	$ 5,237
Interest, net	487	563
Unrealized (gains) and losses	1,845	0
Income before income taxes	2,822	4,674
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income (loss):	3,927	4,052
Walmart International
Segment Reporting Information [Line Items]
Operating income (loss):	1,265	1,139
Sam's Club
Segment Reporting Information [Line Items]
Operating income (loss):	325	399
Corporate and support
Segment Reporting Information [Line Items]
Operating income (loss):	$ (363)	$ (353)

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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