Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017	Aug. 01, 2018	Feb. 01, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in JD, cost basis	$ 3,391
Investment in JD, carrying value		$ 5,037
Investment in JD, fair value	3,583				$ 7,106
Unrealized Gain (Loss) on Investments	(3,516)	0	$ 0
(Gains) and losses for disposal of business operations	(4,850)	0	$ 0
Asset impairment charges		1,400
Walmart Brazil [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Disposal Group, Including Discontinued Operation, Assets				$ 3,300
Disposal Group, Including Discontinued Operation, Assets, Current				1,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Current				1,600
Disposal Group, Including Discontinued Operation, Other Assets				$ 700
(Gains) and losses for disposal of business operations	(4,800)
JD [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain (Loss) on Investments	(3,500)
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in JD, cost basis	1,901
Investment in JD, carrying value		3,547
Investment in JD, fair value	1,791				3,547
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in JD, cost basis	1,490	$ 1,490
Investment in JD, fair value	$ 1,792				$ 3,559