Segments and Disaggregated Revenue (Revenue from Contract with Customer Excluding Assessed Tax, Sam's Club) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2020
Revenue from External Customer [Line Items]
Net sales	$ 567,762	$ 555,233	$ 519,926
Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	73,556	63,910	58,792
Sams Club [Member] | E Commerce [Member]
Revenue from External Customer [Line Items]
Net sales	6,900	5,300	3,800
Grocery and consumables [Member] | Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	46,822	42,148	35,043
Fuel, tobacco, and other categories [Member] | Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	11,048	7,838	10,571
Home and apparel [Member] | Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	8,740	7,092	6,744
Health and Wellness [Member] | Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	3,956	3,792	3,372
Technology, offices, and entertainment [Member] | Sams Club [Member]
Revenue from External Customer [Line Items]
Net sales	$ 2,990	$ 3,040	$ 3,062