Segments and Disaggregated Revenue (Revenue, International) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Revenue from External Customer [Line Items]
Net sales	$ 137,159	$ 133,672
Walmart International
Revenue from External Customer [Line Items]
Net sales	27,300	29,766
Mexico and Central America | Walmart International
Revenue from External Customer [Line Items]
Net sales	8,330	8,496
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Net sales	3,811	7,132
Canada | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,848	4,286
China | Walmart International
Revenue from External Customer [Line Items]
Net sales	3,773	3,368
Other | Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 6,538	$ 6,484