Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Net Income Per Common Share [Line Items]
Income from continuing operations	$ 2,276	$ 3,152
Consolidated net income attributable to noncontrolling interest	(142)	(113)
Income from continuing operations attributable to Walmart	$ 2,134	$ 3,039
Weighted-average common shares outstanding, basic	2,950	3,035
Dilutive impact of stock options and other share-based awards	17	12
Weighted-average common shares outstanding, diluted	2,967	3,047
Basic income per common share from continuing operations attributable to Walmart	$ 0.72	$ 1.00
Diluted income per common share from continuing operations attributable to Walmart	$ 0.72	$ 1.00