Acquisitions 1 (Details) - USD ($) $ in Millions					12 Months Ended	15 Months Ended
		Mar. 31, 2017	Jan. 18, 2017	Jul. 08, 2015	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Mar. 31, 2015
Acquisition purchase price allocation
Goodwill		$ 6,857			$ 6,857		$ 6,086	$ 5,806
Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)					2 years
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			$ 174
Goodwill		312			312
Deferred tax liabilities, net		(115)			(115)
Other assets net of other liabilities assumed	[2]	31			31
Purchase price		675			675
Automic | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets		273			273
Veracode
Business Acquisition
Cash acquired from acquisition		16
Acquisition purchase price allocation
Finite-lived intangible assets	[1]	93			93
Goodwill		429			429
Deferred tax liabilities, net		(96)			(96)
Other assets net of other liabilities assumed	[2]	(19)			(19)
Purchase price		618			618
Veracode | Purchased Software
Acquisition purchase price allocation
Finite-lived intangible assets		$ 211			$ 211
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]				15 years
Fiscal Year 2017 Acquisitions | Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)					3 years
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 net of other liabilities assumed	[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 net of other liabilities assumed						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.