Segments (Segment Net Sales) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 113,204	$ 109,516	$ 339,010	$ 321,569
Walmart U.S. [Member]
Segment Reporting Information [Line Items]
Net sales	66,127	63,835	199,825	191,397
Walmart International [Member]
Segment Reporting Information [Line Items]
Net sales	33,159	32,383	97,252	90,387
Sam's Club [Member]
Segment Reporting Information [Line Items]
Net sales	$ 13,918	$ 13,298	$ 41,933	$ 39,785
Africa [Member]
Segment Reporting Information [Line Items]
Number of Countries in which Entity Operates	12		12
Central America [Member]
Segment Reporting Information [Line Items]
Number of Countries in which Entity Operates	5		5