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, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Segment Reporting Information [Line Items]
Operating income	$ 6,116	$ 5,878	$ 19,201	$ 18,157
Interest, net	547	535	1,587	1,631
Income from continuing operations before income taxes	5,569	5,343	17,614	16,526
Walmart U.S. [Member]
Segment Reporting Information [Line Items]
Operating income	4,844	4,634	15,128	14,280
Walmart International [Member]
Segment Reporting Information [Line Items]
Operating income	1,455	1,389	4,258	3,885
Sam's Club [Member]
Segment Reporting Information [Line Items]
Operating income	435	386	1,461	1,328
Other unallocated [Member]
Segment Reporting Information [Line Items]
Operating income	$ (618)	$ (531)	$ (1,646)	$ (1,336)