Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Earnings Per Share [Abstract]
Consolidated net income (loss)	$ 3,680	$ (727)	$ 7,586	$ 1,549
Consolidated net income attributable to noncontrolling interest	(70)	(134)	(134)	(276)
Consolidated net income (loss) attributable to Walmart	$ 3,610	$ (861)	$ 7,452	$ 1,273
Weighted-average common shares outstanding, basic (shares)	2,853	2,946	2,861	2,948
Dilutive impact of share-based awards (shares)	16	0	17	15
Weighted-average common shares outstanding, diluted (shares)	2,869	2,946	2,878	2,963
Basic (dollars per share)	$ 1.27	$ (0.29)	$ 2.60	$ 0.43
Diluted (dollars per share)	$ 1.26	$ (0.29)	$ 2.59	$ 0.43