Segments and Disaggregated Revenue Revenue from Contract with Customer Excluding Assessed Tax, Walmart US (Details) - Walmart U.S. $ in Millions	3 Months Ended
	Apr. 30, 2018 USD ($)
Grocery [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 43,860
General merchandise [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	24,174
Health and wellness [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	9,128
Other categories [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	586
Product and services, total [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 77,748