Acquisitions 1 (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Sep. 30, 2015	Sep. 30, 2015	Jul. 08, 2015	Mar. 31, 2015
Purchase price allocation and estimated useful lives
Goodwill		$ 6,120	$ 6,120		$ 5,806
Estimated useful life
Goodwill, Estimated useful life			Indefinite
Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)			1 year
Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)			15 years
Purchased Software | Minimum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)			5 years
Purchased Software | Maximum
Estimated useful life
Finite-lived intangible assets, Estimated useful life (in years)			7 years
Rally
Business Acquisition
Cash acquired from Rally		13
Short-term investments acquired from Rally		48
Purchase price allocation and estimated useful lives
Finite-lived intangible assets	[1]	78	$ 78
Goodwill		256	256
Deferred tax liabilities, net		(56)	(56)
Other assets net of other liabilities assumed	[2]	51	51
Purchase price		519	519	$ 519
Rally | Purchased Software
Purchase price allocation and estimated useful lives
Finite-lived intangible assets		190	190
Other Fiscal Year 2016 Acquisitions
Purchase price allocation and estimated useful lives
Finite-lived intangible assets	[1]	14	14
Goodwill		60	60
Deferred tax liabilities, net		(23)	(23)
Other assets net of other liabilities assumed		2	2
Purchase price		146	146
Other Fiscal Year 2016 Acquisitions | Purchased Software
Purchase price allocation and estimated useful lives
Finite-lived intangible assets		$ 93	$ 93

[1] Includes customer relationships and trade names.

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