Segments Revenue from Contract with Customer Excluding Assessed Tax, Walmart US (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 U.S.
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									331,666	$ 318,477	$ 307,833
Walmart U.S. | eCommerceMember
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									15,700
Grocery [Member] | Walmart U.S.
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									184,202
General Merchandise [Member] | Walmart U.S.
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									108,739
Health and Wellness [Member] | Walmart U.S.
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									35,788
Other Categories [Member] | Walmart U.S.
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 2,937