Segments (Segment Operating Income, Income Expense, Net And Income From Continuing Operations Before Income Taxes) (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]
Operating income	$ 5,878	$ 5,611	$ 18,157	$ 17,538
Interest expense, net	(535)	(516)	(1,631)	(1,472)
Income from continuing operations before income taxes	5,343	5,095	16,526	16,066
Walmart U.S. [Member]
Segment Reporting Information [Line Items]
Operating income	4,627	4,402	14,262	13,898
Walmart International [Member]
Segment Reporting Information [Line Items]
Operating income	1,397	1,223	3,908	3,605
Sam's Club [Member]
Segment Reporting Information [Line Items]
Operating income	390	367	1,341	1,224
Other unallocated [Member]
Segment Reporting Information [Line Items]
Operating income	$ (536)	$ (381)	$ (1,354)	$ (1,189)