Goodwill And Acquisition-Related Intangibles, Net (Schedule Of Acquisition-Related Intangibles) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 833	$ 833
Accumulated amortization	(656)	(580)
Acquisition-related intangibles, net	177	253
Developed And Core Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	531	527
Accumulated amortization	(385)	(324)
Acquisition-related intangibles, net	146	203
Trade Names And Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	130	130
Accumulated amortization	(105)	(99)
Acquisition-related intangibles, net	25	31
Registered User Base And Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	87	87
Accumulated amortization	(87)	(84)
Acquisition-related intangibles, net	0	3
Carrier Contracts And Related
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	85	85
Accumulated amortization	(79)	(73)
Acquisition-related intangibles, net	6	12
In-Process Research And Development
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	0	4
Accumulated amortization	0	0
Acquisition-related intangibles, net	$ 0	$ 4