Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Earnings Per Share [Abstract]
Consolidated net income	$ 3,321	$ 1,817	$ 10,907	$ 3,366
Consolidated net income attributable to noncontrolling interest	(33)	(107)	(167)	(383)
Consolidated net income attributable to Walmart	$ 3,288	$ 1,710	$ 10,740	$ 2,983
Weighted-average common shares outstanding, basic (shares)	2,843	2,924	2,855	2,940
Dilutive impact of share-based awards (shares)	18	17	17	16
Weighted-average common shares outstanding, diluted (shares)	2,861	2,941	2,872	2,956
Basic (dollars per share)	$ 1.16	$ 0.58	$ 3.76	$ 1.01
Diluted (dollars per share)	$ 1.15	$ 0.58	$ 3.74	$ 1.01