Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020 USD ($)	Oct. 31, 2019 USD ($)	Oct. 31, 2020 USD ($) segment	Oct. 31, 2019 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment			3
Net sales	$ 133,752	$ 126,981	$ 404,248	$ 379,318
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	88,353	83,189	270,378	248,733
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,554	29,167	86,487	87,081
Sam's Club
Revenue from External Customer [Line Items]
Net sales	15,845	14,625	47,383	43,504
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	10,300	5,700	29,100	15,800
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,300	2,900	10,500	7,900
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 1,300	$ 900	$ 3,700	$ 2,600