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, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Segment Reporting Information [Line Items]
Operating income	$ 6,265	$ 6,310	$ 19,198	$ 19,525
Interest, net	656	580	1,762	1,662
Income from continuing operations before income taxes	5,609	5,730	17,436	17,863
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income	4,932	4,991	15,159	15,571
Walmart International
Segment Reporting Information [Line Items]
Operating income	1,430	1,379	4,121	3,921
Sam's Club
Segment Reporting Information [Line Items]
Operating income	493	440	1,466	1,448
Corporate and support
Segment Reporting Information [Line Items]
Operating income	$ (590)	$ (500)	$ (1,548)	$ (1,415)