Debt (Narrative) (Details)					3 Months Ended			6 Months Ended
	May 11, 2020 USD ($)	Apr. 07, 2020 USD ($)	Sep. 26, 2019 USD ($)	Sep. 12, 2017 USD ($) extension	Jul. 31, 2020 USD ($)	Aug. 02, 2019 USD ($)		Jul. 31, 2020 USD ($)	Aug. 02, 2019 USD ($)		Jan. 31, 2020 USD ($)
Debt Instrument [Line Items]
Interest expense					$ 55,000,000	$ 34,000,000	[1]	$ 104,000,000	$ 68,000,000	[1]
Long-term debt					$ 4,714,000,000			4,714,000,000			$ 2,731,000,000
Unsecured Debt | Term Loan
Debt Instrument [Line Items]
Interest expense								$ 14,000,000
Line of credit term			364 days
Term loan maximum borrowing capacity			$ 2,000,000,000.0
Weighted-average interest rate					1.05%			1.05%
Short-term debt					$ 1,500,000,000			$ 1,500,000,000			1,500,000,000
Unsecured Debt | Minimum | London interbank offered rate | Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.75%
Unsecured Debt | Minimum | Base rate | Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.00%
Unsecured Debt | Maximum | London interbank offered rate | Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.25%
Unsecured Debt | Maximum | Base rate | Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.25%
Senior Notes
Debt Instrument [Line Items]
Proceeds from debt issuance		$ 2,000,000,000.0
Debt discount		3,000,000			7,000,000			7,000,000			5,000,000
Debt issuance costs		$ 17,000,000
Interest expense					49,000,000	$ 32,000,000		$ 88,000,000	$ 65,000,000
Repurchase price as percent of principal								101.00%
Long-term debt					4,714,000,000			$ 4,714,000,000			3,979,000,000
Senior Notes | Note Due August 2020
Debt Instrument [Line Items]
Long-term debt	$ 1,300,000,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity				$ 1,000,000,000.0
Line of credit term				5 years
Number of line of credit term extensions | extension				2
Line of credit term extension duration				1 year
Long-term debt					$ 0			$ 0			$ 0

[1] Adjusted to reflect the recast of prior period information due to the Pivotal Software, Inc. (“Pivotal”) acquisition in fiscal 2020, which was accounted for as a transaction between entities under common control (refer to Note A).