Certain Financial Statement Information - Schedule of Purchase-related intangibles (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Schedule of Purchased Intangible assets
Gross Assets	$ 517,336	$ 517,336
Accumulated Amortization and Impairments	(505,345)	(500,702)
Net Assets	11,991	16,634
Developed technology/in-process research and development [Member]
Schedule of Purchased Intangible assets
Gross Assets	441,300	441,300
Accumulated Amortization and Impairments	(431,771)	(429,054)
Net Assets	9,529	12,246
Weighted average remaining useful life	3 years 6 months	4 years 7 months 6 days
Customer relationships [Member]
Schedule of Purchased Intangible assets
Gross Assets	12,830	12,830
Accumulated Amortization and Impairments	(10,507)	(8,881)
Net Assets	2,323	3,949
Weighted average remaining useful life	2 years 1 month 6 days	2 years 10 months 24 days
Patents/core technology rights/tradename [Member]
Schedule of Purchased Intangible assets
Gross Assets	63,206	63,206
Accumulated Amortization and Impairments	(63,067)	(62,767)
Net Assets	$ 139	$ 439
Weighted average remaining useful life	3 months 18 days	1 year 6 months