Segments and Disaggregated Revenue (Revenue, International) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Revenue from External Customer [Line Items]
Net sales	$ 136,824	$ 129,388	$ 270,496	$ 252,337
Walmart International
Revenue from External Customer [Line Items]
Net sales	27,167	29,139	56,933	57,914
Mexico and Central America | Walmart International
Revenue from External Customer [Line Items]
Net sales	7,208	8,014	15,704	15,852
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Net sales	6,698	7,316	13,830	14,393
Canada | Walmart International
Revenue from External Customer [Line Items]
Net sales	5,127	4,635	9,413	8,758
China | Walmart International
Revenue from External Customer [Line Items]
Net sales	2,579	2,428	5,947	5,491
Other | Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 5,555	$ 6,746	$ 12,039	$ 13,420