Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Net Income Per Common Share [Line Items]
Income from continuing operations	$ 3,104	$ 3,889	$ 6,256	$ 7,105
Consolidated net income attributable to noncontrolling interest	(205)	(116)	(318)	(253)
Income from continuing operations attributable to Walmart	$ 2,899	$ 3,773	$ 5,938	$ 6,852
Weighted-average common shares outstanding, basic	3,008	3,109	3,021	3,126
Dilutive impact of stock options and other share-based awards	13	10	13	10
Weighted-average common shares outstanding, diluted	3,021	3,119	3,034	3,136
Basic income per common share from continuing operations attributable to Walmart	$ 0.96	$ 1.21	$ 1.97	$ 2.19
Diluted income per common share from continuing operations attributable to Walmart	$ 0.96	$ 1.21	$ 1.96	$ 2.18