Net Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Net Income Per Common Share [Line Items]
Consolidated net income	$ 3,906	$ 2,276
Consolidated net income attributable to noncontrolling interest	(64)	(142)
Consolidated net income attributable to Walmart	$ 3,842	$ 2,134
Weighted-average common shares outstanding, basic (shares)	2,869	2,950
Dilutive impact of share-based awards (shares)	17	17
Weighted-average common shares outstanding, diluted (shares)	2,886	2,967
Basic (dollars per share)	$ 1.34	$ 0.72
Diluted (dollars per share)	$ 1.33	$ 0.72