Segments and Disaggregated Revenue (Revenue, Sam's Club) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Revenue from External Customer [Line Items]
Net sales	$ 140,288	$ 137,159
Sam's Club
Revenue from External Customer [Line Items]
Net sales	19,621	16,692
Sam's Club | eCommerceMember
Revenue from External Customer [Line Items]
Net sales	1,900	1,500
Sam's Club | Grocery and consumables
Revenue from External Customer [Line Items]
Net sales	12,301	10,669
Sam's Club | Fuel, tobacco and other categories
Revenue from External Customer [Line Items]
Net sales	3,623	2,299
Sam's Club | Home and apparel
Revenue from External Customer [Line Items]
Net sales	2,050	2,082
Sam's Club | Health and wellness
Revenue from External Customer [Line Items]
Net sales	1,010	941
Sam's Club | Technology, office and entertainment
Revenue from External Customer [Line Items]
Net sales	$ 637	$ 701