Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Condensed Consolidated Statements Of Operations [Abstract]
Net revenues	$ 56,347	$ 62,364	$ 182,120	$ 189,127
Cost of revenues	23,795	23,886	77,830	69,806
Gross profit	32,552	38,478	104,290	119,321
Operating expenses:
Research and development	28,279	28,684	86,256	81,800
Selling, general and administrative	11,406	12,729	32,903	37,440
Amortization of purchased intangible assets	650	1,488	2,552	3,572
Restructuring charges, net	2	33	875	566
Total operating expenses	40,337	42,934	122,586	123,378
Operating loss	(7,785)	(4,456)	(18,296)	(4,057)
Interest income, net	828	2,199	3,578	6,780
Other income, net	86	126	209	728
(Loss) income before income taxes	(6,871)	(2,131)	(14,509)	3,451
Income tax expense (benefit)	206	(170)	597	446
Net (loss) income	$ (7,077)	$ (1,961)	$ (15,106)	$ 3,005
Basic net (loss) income per share	$ (0.12)	$ (0.03)	$ (0.24)	$ 0.05
Shares used in calculating basic net (loss) income per share	60,990	64,647	62,465	65,468
Diluted net (loss) income per share	$ (0.12)	$ (0.03)	$ (0.24)	$ 0.04
Shares used in calculating diluted net (loss) income per share	60,990	64,647	62,465	67,549