Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Net Income Per Common Share [Line Items]
Income from continuing operations	$ (727)	$ 3,104	$ 1,549	$ 6,256
Consolidated net income attributable to noncontrolling interest	(134)	(205)	(276)	(318)
Income from continuing operations attributable to Walmart	$ (861)	$ 2,899	$ 1,273	$ 5,938
Weighted-average common shares outstanding, basic	2,946	3,008	2,948	3,021
Dilutive impact of stock options and other share-based awards	0	13	15	13
Weighted-average common shares outstanding, diluted	2,946	3,021	2,963	3,034
Basic income per common share from continuing operations attributable to Walmart	$ (0.29)	$ 0.96	$ 0.43	$ 1.97
Diluted income per common share from continuing operations attributable to Walmart	$ (0.29)	$ 0.96	$ 0.43	$ 1.96