Segments and Disaggregated Revenue (Revenue, International) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Revenue from External Customer [Line Items]
Net sales	$ 133,752	$ 126,981	$ 404,248	$ 379,318
Walmart International
Revenue from External Customer [Line Items]
Net sales	29,554	29,167	86,487	87,081
Mexico and Central America | Walmart International
Revenue from External Customer [Line Items]
Net sales	7,429	7,913	23,133	23,765
United Kingdom | Walmart International
Revenue from External Customer [Line Items]
Net sales	7,249	6,961	21,079	21,355
Canada | Walmart International
Revenue from External Customer [Line Items]
Net sales	4,969	4,608	14,383	13,366
China | Walmart International
Revenue from External Customer [Line Items]
Net sales	2,787	2,718	8,735	8,209
Other | Walmart International
Revenue from External Customer [Line Items]
Net sales	$ 7,120	$ 6,967	$ 19,157	$ 20,386