Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 31, 2018	Jul. 31, 2018	Jul. 31, 2017	Jan. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Gain) Loss on Disposition of Business		$ 4,755	$ 0
Asset Impairment Charges				$ 1,400
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, Current	1,600	1,600
Disposal Group, Including Discontinued Operation, Other Assets	700	$ 700
(Gain) Loss on Disposition of Business	$ 4,800
Sam's Club
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges				600
Walmart International
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges				$ 200