Divestitures (Details) - USD ($) $ in Millions	6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Apr. 30, 2021	Mar. 31, 2021	Feb. 28, 2021	Jan. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets	$ 238,552	$ 237,382				$ 252,496
Losses on disposal of business operations	433	$ 37
Walmart International
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets	87,800					$ 109,400
Asda | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from divestiture					$ 9,600
Losses on disposal of business operations	200
Seiyu
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest percentage			15.00%
Seiyu | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from divestiture				$ 1,200
Losses on disposal of business operations	$ 200