Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended	12 Months Ended
	Aug. 03, 2019 USD ($)	Feb. 01, 2020 USD ($) segment	Feb. 02, 2019 USD ($)	Feb. 03, 2018 USD ($)	Oct. 01, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of Operating Segments | segment		2
Operating leases		$ 2,709,000,000
Operating lease liability		2,798,000,000
Cash Equivalents, at Carrying Value		$ 1,668,000,000	$ 1,410,000,000
Weighted Average Interest Rate on Cash Equivalents		1.80%	2.50%
Allowances for uncollectible receivables		$ 24,000,000	$ 23,000,000
Goodwill		$ 984,000,000	$ 915,000,000		$ 490,000,000
Percentage of Commissions on Sale of Extended Warranties to Revenue		2.00%	2.00%	2.00%
Gift card redemption within 1 year, percentage		90.00%
Revenue recognized that was included in the contract liability balance as of February 4, 2018		$ 890,000,000	$ 871,000,000
Period of Expiration for Customer Loyalty Certificates, Low End of Range		2 months
Period of Expiration for Customer Loyalty Certificates, High End of Range		6 months
Advertising expense		$ 840,000,000	$ 777,000,000	$ 776,000,000
Branded cards		25.00%	25.00%	25.00%
2021 Notes [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt		$ 650,000,000
2028 Notes [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt		500,000,000
Best Buy Health [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill		541,000,000
Best Buy Domestic [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill		443,000,000
Best Buy Gift Cards [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue recognized that was included in the contract liability balance as of February 4, 2018		$ 35,000,000	$ 34,000,000	$ 40,000,000
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases	$ 2,700,000,000		$ 2,732,000,000
Operating lease liability	2,800,000,000
retained earnings	(22,000,000)
retained earnings, net of tax	$ 3,000,000
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of contract		1 month
Customer loyalty program, certificate expiration period		1 month
Minimum [Member] | Software [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives		2 years
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of contract		3 years
Customer loyalty program, certificate expiration period		5 years
Maximum [Member] | Software [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives		7 years