Condensed Consolidated Statements Of Operations (USD $) In Millions, except Per Share data	3 Months Ended		6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Operations [Abstract]
Net revenue	$ 715	$ 631	$ 1,714	$ 1,446
Cost of goods sold	432	363	672	585
Gross profit	283	268	1,042	861
Operating expenses:
Marketing and sales	222	173	362	300
General and administrative	88	77	162	151
Research and development	318	277	603	552
Amortization of intangibles	13	15	26	30
Acquisition-related contingent consideration	17	(28)	19	(26)
Restructuring and other charges	(1)	6	17	8
Total operating expenses	657	520	1,189	1,015
Operating loss	(374)	(252)	(147)	(154)
Gain on strategic investments, net		28		23
Interest and other income (expense), net	(6)	6	(3)	6
Loss before benefit from income taxes	(380)	(218)	(150)	(125)
Benefit from income taxes	(40)	(17)	(31)	(20)
Net loss	$ (340)	$ (201)	$ (119)	$ (105)
Net loss per share:
Basic and Diluted	$ (1.03)	$ (0.61)	$ (0.36)	$ (0.32)
Number of shares used in computation:
Basic and Diluted	331	329	331	328