Segments Schedule of Segment Reporting Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 137,743	$ 123,897	$ 127,059	$ 121,630	$ 135,150	$ 122,136	$ 121,949	$ 116,526	$ 510,329	$ 495,761	$ 481,317
Operating Income (Loss)									21,957	20,437	22,764
Interest Income (Expense), Net									(2,129)	(2,178)	(2,267)
Gain (Loss) on Extinguishment of Debt									0	(3,136)	0
Nonoperating Income (Expense)									(8,368)	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									11,460	15,123	20,497
Assets	219,295				204,522				219,295	204,522	198,825
Depreciation, Depletion and Amortization									10,678	10,529	10,080
Payments to Acquire Property, Plant, and Equipment									10,344	10,051	10,619
Walmart U.S.
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									331,666	318,477	307,833
Operating Income (Loss)									17,386	16,995	17,012
Assets	105,114				104,347				105,114	104,347	104,262
Depreciation, Depletion and Amortization									6,201	6,005	5,598
Payments to Acquire Property, Plant, and Equipment									6,034	5,680	6,090
Walmart International
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									120,824	118,068	116,119
Operating Income (Loss)									4,883	5,229	5,737
Assets	97,066				81,549				97,066	81,549	74,508
Depreciation, Depletion and Amortization									2,590	2,601	2,629
Payments to Acquire Property, Plant, and Equipment									2,661	2,607	2,697
Sam's Club
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									57,839	59,216	57,365
Operating Income (Loss)									1,520	915	1,628
Assets	12,893				13,418				12,893	13,418	14,125
Depreciation, Depletion and Amortization									639	698	712
Payments to Acquire Property, Plant, and Equipment									450	626	639
Corporate and support
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									0	0	0
Operating Income (Loss)									(1,832)	(2,702)	(1,613)
Assets	$ 4,222				$ 5,208				4,222	5,208	5,930
Depreciation, Depletion and Amortization									1,248	1,225	1,141
Payments to Acquire Property, Plant, and Equipment									$ 1,199	$ 1,138	$ 1,193