Goodwill And Acquisition-Related Intangibles, Net (Schedule Of Acquisition-Related Intangibles) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 833	$ 833
Accumulated Amortization	(599)	(580)
Acquisition-Related Intangibles, Net	234	253	[1]
Developed And Core Technology
Finite-Lived Intangible Assets
Gross Carrying Amount	527	527
Accumulated Amortization	(339)	(324)
Acquisition-Related Intangibles, Net	188	203
Trade Names And Trademarks
Finite-Lived Intangible Assets
Gross Carrying Amount	130	130
Accumulated Amortization	(101)	(99)
Acquisition-Related Intangibles, Net	29	31
Registered User Base And Other Intangibles
Finite-Lived Intangible Assets
Gross Carrying Amount	87	87
Accumulated Amortization	(85)	(84)
Acquisition-Related Intangibles, Net	2	3
Carrier Contracts And Related
Finite-Lived Intangible Assets
Gross Carrying Amount	85	85
Accumulated Amortization	(74)	(73)
Acquisition-Related Intangibles, Net	11	12
In-Process Research And Development
Finite-Lived Intangible Assets
Gross Carrying Amount	4	4
Accumulated Amortization	0	0
Acquisition-Related Intangibles, Net	$ 4	$ 4

[1] Derived from audited consolidated financial statements.