Segments and Disaggregated Revenue - Net Sales (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 133,752	$ 126,981	$ 404,248	$ 379,318
Walmart U.S.
Segment Reporting Information [Line Items]
Net sales	88,353	83,189	270,378	248,733
Walmart International
Segment Reporting Information [Line Items]
Net sales	29,554	29,167	86,487	87,081
Sam's Club
Segment Reporting Information [Line Items]
Net sales	$ 15,845	$ 14,625	$ 47,383	$ 43,504