Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Disposition of Business	$ 1	$ (4,846)
Walmart Brazil [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Disposal Group, Including Discontinued Operation, Assets			$ 3,300
Disposal Group, Including Discontinued Operation, Assets, Current			1,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment			1,600
Disposal Group, Including Discontinued Operation, Other Assets			$ 700
Gain (Loss) on Disposition of Business		$ (4,800)