Segment Net Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 127,059	$ 121,949	$ 248,689	$ 238,475
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	82,815	78,738	160,563	154,174
Walmart International
Segment Reporting Information [Line Items]
Net sales	29,454	28,331	59,714	55,428
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 14,790	$ 14,880	$ 28,412	$ 28,873