Acquisitions 1 (Details) - USD ($) $ in Millions					12 Months Ended	15 Months Ended
		Mar. 31, 2017	Jan. 18, 2017	Jul. 08, 2015	Mar. 31, 2018	Mar. 31, 2018	Jun. 30, 2016	Dec. 31, 2017	Mar. 31, 2016
Acquisition purchase price allocation
Goodwill		$ 6,857			$ 6,804	$ 6,804			$ 6,086
Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)					1 year
Purchased Software | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)					10 years
Automic
Business Acquisition
Cash acquired from acquisition			$ 34
Acquisition purchase price allocation
Finite-lived intangible assets	[1]							$ 174
Goodwill								303
Deferred tax liabilities, net								(92)
Other assets (liabilities), net	[2]							17
Purchase price								675
Automic | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets								$ 273
Veracode
Business Acquisition
Cash acquired from acquisition		$ 16
Acquisition purchase price allocation
Finite-lived intangible assets	[1]				$ 99	99
Goodwill					336	336
Deferred tax liabilities, net					(33)	(33)
Other assets (liabilities), net	[2]				(24)	(24)
Purchase price					618	618
Veracode | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets					$ 240	$ 240
Fiscal Year 2017 Acquisitions
Estimated useful life
Goodwill, Estimated useful life						Indefinite
Fiscal Year 2017 Acquisitions | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)	[1]					2 years
Fiscal Year 2017 Acquisitions | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)	[1]					12 years
Fiscal Year 2017 Acquisitions | Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)						1 year
Fiscal Year 2017 Acquisitions | Purchased Software | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)						8 years
Rally
Business Acquisition
Cash acquired from acquisition				$ 13
Short-term investments acquired from acquisition				$ 48
Acquisition purchase price allocation
Finite-lived intangible assets	[1]						$ 78
Goodwill							257
Deferred tax liabilities, net							(45)
Other assets (liabilities), net	[3]						51
Purchase price							519
Rally | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets							178
Other Fiscal Year 2016 Acquisitions
Acquisition purchase price allocation
Finite-lived intangible assets	[1]						14
Goodwill							59
Deferred tax liabilities, net							(24)
Other assets (liabilities), net							2
Purchase price							147
Other Fiscal Year 2016 Acquisitions | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets							$ 96
Fiscal Year 2016 Acquisitions
Estimated useful life
Goodwill, Estimated useful life							Indefinite
Fiscal Year 2016 Acquisitions | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)	[1]						1 year
Fiscal Year 2016 Acquisitions | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)	[1]						15 years
Fiscal Year 2016 Acquisitions | Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)							5 years
Fiscal Year 2016 Acquisitions | Purchased Software | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)							7 years

[1] Includes customer relationships and trade names.

[2] Includes approximately $34 million and $16 million of cash acquired from Automic and Veracode, respectively.

[3] Includes approximately $13 million of cash and approximately $48 million of short-term investments acquired relating to Rally.