Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Jan. 31, 2019 USD ($)	Jan. 31, 2018 USD ($)	Jan. 31, 2017 USD ($)	Apr. 30, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Customers per week, approximate	275,000,000
Number of stores	11,300
Banners	58
Number of countries	27
Amounts due from banks	$ 1,400	$ 1,600
Cash and cash equivalents	7,722	6,756
Cash Held in Foreign Countries	7,700	6,800
Nonrepatriable Cash and Cash Equivalents	2,800	1,400
Nonrepatriable Cash and Cash Equivalents, Flipkart	1,200
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	40
Depreciation and amortization of property and equipment, property under financing obligations and property under capital leases	10,700	10,500	$ 10,100
Advertising expense	$ 3,500	3,100	2,900
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Global intangible low-taxed income, 2018 through 2025	10.50%
Global intangible low-taxed income, 2025 Thereafter	13.125%
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 924
Deferred Revenue, Revenue Recognized	1,400	1,400	$ 1,400
Restricted cash recorded as noncurrent asset	34	$ 300
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 2,600
Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 15,000
ASU 2016-02, Recognition of Operating Lease Assets and Liabilities				17,500
ASU 2016-02, Derecognition of Financial Obligation Assets and Liabilities				$ 3,000