Segment Net Sales (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 117,176	$ 116,598	$ 351,567	$ 349,930
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	74,550	72,712	224,086	216,916
Walmart International
Segment Reporting Information [Line Items]
Net sales	28,390	29,811	85,094	90,726
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 14,236	$ 14,075	$ 42,387	$ 42,288