Quarterly Financial Data (unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 136,267	$ 123,179	$ 123,355	$ 117,542	$ 130,936	$ 118,179	$ 120,854	$ 115,904	$ 500,343	$ 485,873	$ 482,130
Net sales	135,150	122,136	121,949	116,526	129,750	117,176	119,405	114,986	495,761	481,317	478,614
Cost of sales	102,640	91,547	91,521	87,688	97,743	87,484	89,485	86,544	373,396	361,256	360,984
Consolidated net income	2,363	1,904	3,104	3,152	3,986	3,202	3,889	3,216	10,523	14,293	15,080
Consolidated net income attributable to Walmart	$ 2,175	$ 1,749	$ 2,899	$ 3,039	$ 3,757	$ 3,034	$ 3,773	$ 3,079	$ 9,862	$ 13,643	$ 14,694
Basic net income per common share attributable to Walmart	$ 0.74	$ 0.59	$ 0.96	$ 1.00	$ 1.23	$ 0.98	$ 1.21	$ 0.98	$ 3.29	$ 4.40	$ 4.58
Diluted net income per common share attributable to Walmart	$ 0.73	$ 0.58	$ 0.96	$ 1.00	$ 1.22	$ 0.98	$ 1.21	$ 0.98	$ 3.28	$ 4.38	$ 4.57