Segments Revenue from Contract with Customer Excluding Assessed Tax, International (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 137,743	$ 123,897	$ 127,059	$ 121,630	$ 135,150	$ 122,136	$ 121,949	$ 116,526	$ 510,329	$ 495,761	$ 481,317
Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									120,824	$ 118,068	$ 116,119
Walmart International | eCommerceMember
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									6,700
Mexico and Central America [Member] | Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									31,790
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									30,547
CANADA | Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									18,613
CHINA | Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									10,702
Other [Member] | Walmart International
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 29,172