Segments and Disaggregated Revenue (Revenue from Contract with Customer Excluding Assessed Tax Walmart U.S) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Revenue from External Customer [Line Items]
Net sales	$ 555,233	$ 519,926	$ 510,329
Walmart U S [Member]
Revenue from External Customer [Line Items]
Net sales	369,963	341,004	$ 331,666
Walmart U S [Member] | E Commerce [Member]
Revenue from External Customer [Line Items]
Net sales	43,000	24,100
Grocery [Member] | Walmart U S [Member]
Revenue from External Customer [Line Items]
Net sales	208,413	192,428
General Merchandise [Member] | Walmart U S [Member]
Revenue from External Customer [Line Items]
Net sales	119,406	108,687
Health and Wellness [Member] | Walmart U S [Member]
Revenue from External Customer [Line Items]
Net sales	38,522	36,558
Other Categories [Member] | Walmart U S [Member]
Revenue from External Customer [Line Items]
Net sales	$ 3,622	$ 3,331