Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020 USD ($)	Jul. 31, 2019 USD ($)	Jul. 31, 2020 USD ($) segment	Jul. 31, 2019 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment			3
Net sales	$ 136,824	$ 129,388	$ 270,496	$ 252,337
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	93,282	85,200	182,025	165,544
Walmart International
Revenue from External Customer [Line Items]
Net sales	27,167	29,139	56,933	57,914
Sam's Club
Revenue from External Customer [Line Items]
Net sales	16,375	15,049	31,538	28,879
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	10,500	5,400	18,800	10,100
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	3,300	2,600	6,200	5,100
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 1,300	$ 1,000	$ 2,300	$ 1,700