Segment Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Segment Reporting Information [Line Items]
Net sales	$ 121,630	$ 116,526
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	77,748	75,436
Walmart International
Segment Reporting Information [Line Items]
Net sales	30,260	27,097
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 13,622	$ 13,993