Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2021 USD ($)	Jul. 31, 2020 USD ($)	Jul. 31, 2021 USD ($) segment	Jul. 31, 2020 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment			3
Net sales	$ 139,871	$ 136,824	$ 277,030	$ 270,496
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	98,192	93,282	191,359	182,025
Walmart International
Revenue from External Customer [Line Items]
Net sales	23,035	27,167	50,335	56,933
Sam's Club
Revenue from External Customer [Line Items]
Net sales	18,644	16,375	35,336	31,538
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	11,200	10,500	22,500	18,800
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,100	3,300	8,400	6,200
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 1,600	$ 1,300	$ 3,200	$ 2,300