Goodwill And Acquisition-Related Intangibles, Net (Schedule Of Acquisition-Related Intangibles) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Finite-Lived Intangible Assets
Gross carrying amount	$ 833	$ 833
Accumulated amortization	(690)	(656)
Acquisition-related intangibles, net	143	177	[1]
Developed And Core Technology
Finite-Lived Intangible Assets
Gross carrying amount	531	531
Accumulated amortization	(413)	(385)
Acquisition-related intangibles, net	118	146
Trade Names And Trademarks
Finite-Lived Intangible Assets
Gross carrying amount	130	130
Accumulated amortization	(108)	(105)
Acquisition-related intangibles, net	22	25
Registered User Base And Other Intangibles
Finite-Lived Intangible Assets
Gross carrying amount	87	87
Accumulated amortization	(87)	(87)
Acquisition-related intangibles, net	0	0
Carrier Contracts And Related
Finite-Lived Intangible Assets
Gross carrying amount	85	85
Accumulated amortization	(82)	(79)
Acquisition-related intangibles, net	$ 3	$ 6

[1] Derived from audited consolidated financial statements.