Segments and Disaggregated Revenue (Narrative) (Details) $ in Millions	3 Months Ended
	Apr. 30, 2021 USD ($) segment	Apr. 30, 2020 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment	3
Net sales	$ 137,159	$ 133,672
Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	93,167	88,743
Walmart International
Revenue from External Customer [Line Items]
Net sales	27,300	29,766
Sam's Club
Revenue from External Customer [Line Items]
Net sales	16,692	15,163
eCommerceMember | Walmart U.S.
Revenue from External Customer [Line Items]
Net sales	11,300	8,300
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,300	2,900
eCommerceMember | Sam's Club
Revenue from External Customer [Line Items]
Net sales	$ 1,500	$ 1,000