Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)	Oct. 31, 2019 USD ($) segment	Oct. 31, 2018 USD ($)
Revenue from External Customer [Line Items]
Number of Reportable Segments | segment			3
Net sales	$ 126,981	$ 123,897	$ 379,318	$ 372,586
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	83,189	80,583	248,733	241,146
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,167	28,793	87,081	88,507
Sam's Club
Revenue from External Customer [Line Items]
Net sales	14,625	14,521	43,504	42,933
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	5,000	3,600	14,000	10,200
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	2,900	1,500	7,900	3,400
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 900	$ 700	$ 2,500	$ 1,900