Segments and Disaggregated Revenue (Revenue, Walmart US) (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 U.S.
Revenue from External Customer [Line Items]
Net sales	98,192	93,282	191,359	182,025
Walmart U.S. | Grocery
Revenue from External Customer [Line Items]
Net sales	54,649	51,545	106,040	104,466
Walmart U.S. | General merchandise
Revenue from External Customer [Line Items]
Net sales	31,707	31,682	62,314	57,148
Walmart U.S. | Health and wellness
Revenue from External Customer [Line Items]
Net sales	10,480	9,154	20,450	18,754
Walmart U.S. | Other categories
Revenue from External Customer [Line Items]
Net sales	$ 1,356	$ 901	$ 2,555	$ 1,657