Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Losses on disposal of business operations		$ 8,401	$ 15	$ 4,850
Asda [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Losses on disposal of business operations	$ 5,500
Accumulated pension components included in disposal group, expected amount		2,300
Walmart Brazil [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discontinued operation, assets				3,300
Discontinued operation, current assets				1,000
Discontinued operation, property and equipment				1,600
Discontinued operation, other assets				$ 700
Walmart International [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Losses on disposal of business operations		$ 8,300
Impairment charges			400
Walmart U S [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges			$ 500