Segments (Segment Net Sales) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Segment Reporting Information [Line Items]
Net sales	$ 109,516	$ 101,239	$ 321,569	$ 303,352
Walmart U.S. [Member]
Segment Reporting Information [Line Items]
Net sales	63,835	62,178	191,397	189,156
Walmart International [Member]
Segment Reporting Information [Line Items]
Net sales	32,383	26,919	90,387	77,850
Sam's Club [Member]
Segment Reporting Information [Line Items]
Net sales	$ 13,298	$ 12,142	$ 39,785	$ 36,346