Goodwill And Acquisition-Related Intangibles, Net (Schedule Of Acquisition-Related Intangibles) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Mar. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	$ 840	$ 520
Acquisition-related intangibles, Accumulated Amortization	(438)	(376)
Acquisition-Related Intangibles, Net	402	144	[1]
Developed And Core Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	518	259
Acquisition-related intangibles, Accumulated Amortization	(212)	(180)
Acquisition-Related Intangibles, Net	306	79
Trade Names And Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	131	90
Acquisition-related intangibles, Accumulated Amortization	(81)	(70)
Acquisition-Related Intangibles, Net	50	20
Carrier Contracts And Related [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	85	85
Acquisition-related intangibles, Accumulated Amortization	(66)	(62)
Acquisition-Related Intangibles, Net	19	23
Registered User Base And Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	91	86
Acquisition-related intangibles, Accumulated Amortization	(79)	(64)
Acquisition-Related Intangibles, Net	12	22
In-Process Research And Development [Member]
Finite-Lived Intangible Assets [Line Items]
Acquisition-related intangibles, Gross Carrying Amount	15
Acquisition-Related Intangibles, Net	$ 15

[1] Derived from audited consolidated financial statements.