Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Net Income Per Common Share [Line Items]
Consolidated net Income	$ 7,179	$ 10,523	$ 14,293
Consolidated net income attributable to noncontrolling interest	(509)	(661)	(650)
Consolidated net income attributable to Walmart	$ 6,670	$ 9,862	$ 13,643
Weighted-average common shares outstanding, basic	2,929	2,995	3,101
Dilutive impact of stock options and other share-based awards	16	15	11
Weighted-average common shares outstanding, diluted	2,945	3,010	3,112
Basic net income per common share attributable to Walmart	$ 2.28	$ 3.29	$ 4.40
Diluted net income per common share attributable to Walmart	$ 2.26	$ 3.28	$ 4.38