Segment Operating Income, Income Expense, Net and Income from Continuing Operations before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Segment Reporting Information [Line Items]
Operating income (loss):	$ 5,969	$ 6,165	$ 11,206	$ 11,440
Interest, net	575	566	1,138	1,127
Loss on Extinguishment of Debt	788	0	788	0
Income from continuing operations before income taxes	4,606	5,599	9,280	10,313
Walmart U.S.
Segment Reporting Information [Line Items]
Operating income (loss):	4,618	4,519	8,887	8,751
Walmart International
Segment Reporting Information [Line Items]
Operating income (loss):	1,592	1,727	2,755	2,891
Sam's Club
Segment Reporting Information [Line Items]
Operating income (loss):	404	472	818	885
Corporate and support
Segment Reporting Information [Line Items]
Operating income (loss):	$ (645)	$ (553)	$ (1,254)	$ (1,087)