Segments and Disaggregated Revenue Revenue from Contract with Customer Excluding Assessed Tax, International (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Revenue from External Customer [Line Items]
Net sales	$ 122,949	$ 121,630
Walmart International
Revenue from External Customer [Line Items]
Net sales	28,775	30,260
Mexico and Central America | Walmart International
Revenue from External Customer [Line Items]
Net sales	7,837	7,684
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Net sales	7,077	7,515
Canada | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,122	4,254
China | Walmart International
Revenue from External Customer [Line Items]
Net sales	3,063	3,205
Other | Walmart International
Revenue from External Customer [Line Items]
Net sales	6,676	7,602
eCommerceMember | Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 2,500	$ 1,000