Segments and Disaggregated Revenue (Revenue, International) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Revenue from External Customer [Line Items]
Net sales	$ 139,871	$ 136,824	$ 277,030	$ 270,496
Walmart International
Revenue from External Customer [Line Items]
Net sales	23,035	27,167	50,335	56,933
Mexico and Central America | Walmart International
Revenue from External Customer [Line Items]
Net sales	8,658	7,208	16,988	15,704
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Net sales	0	6,698	3,811	13,830
Canada | Walmart International
Revenue from External Customer [Line Items]
Net sales	5,492	5,127	10,340	9,413
China | Walmart International
Revenue from External Customer [Line Items]
Net sales	3,001	2,579	6,774	5,947
Other | Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 5,884	$ 5,555	$ 12,422	$ 12,039