Segments and Disaggregated Revenue Revenue from Contract with Customer Excluding Assessed Tax, Walmart US (Details) - Walmart U.S. - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2018
Grocery [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 45,991	$ 89,851
General merchandise [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	27,305	51,479
Health and wellness [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	8,837	17,965
Other categories [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	682	1,268
Product and services, total [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	82,815	160,563
eCommerceMember
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 3,500	$ 6,600