Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2019 USD ($)	Jul. 31, 2018 USD ($)	Jul. 31, 2019 USD ($) segment	Jul. 31, 2018 USD ($)
Revenue from External Customer [Line Items]
Number of Reportable Segments | segment			3
Net sales	$ 129,388	$ 127,059	$ 252,337	$ 248,689
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	85,200	82,815	165,544	160,563
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,139	29,454	57,914	59,714
Sam's Club
Revenue from External Customer [Line Items]
Net sales	15,049	14,790	28,879	28,412
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	4,800	3,500	9,000	6,600
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	2,600	1,000	5,100	1,900
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 900	$ 700	$ 1,600	$ 1,200