Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Disposition of Business		$ 0	$ 4,755
Walmart Brazil [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Disposal Group, Including Discontinued Operation, Assets	$ 3,300		3,300
Disposal Group, Including Discontinued Operation, Assets, Current	1,000		1,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment	1,600		1,600
Disposal Group, Including Discontinued Operation, Other Assets	700		700
Gain (Loss) on Disposition of Business	$ (4,800)		$ (4,800)