Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Consolidated Statements of Operations [Abstract]
Net revenues	$ 46,324	$ 64,929	$ 87,618	$ 125,773
Cost of revenues	20,561	27,704	38,916	54,035
Gross profit	25,763	37,225	48,702	71,738
Operating expenses:
Research and development	34,383	29,609	69,154	57,977
Selling, general and administrative	13,531	8,941	26,001	21,497
Amortization of purchased intangible assets	601	803	1,251	1,902
Restructuring (recoveries) charges, net		(40)		873
Total operating expenses	48,515	39,313	96,406	82,249
Operating loss	(22,752)	(2,088)	(47,704)	(10,511)
Interest income (expense), net	745	1,469	2,424	2,750
Other income (expense), net	90	48	173	123
Loss before income taxes	(21,917)	(571)	(45,107)	(7,638)
Income tax (benefit) expense	(360)	581	(160)	391
Net loss	$ (21,557)	$ (1,152)	$ (44,947)	$ (8,029)
Basic and diluted net loss per share	$ (0.33)	$ (0.02)	$ (0.71)	$ (0.13)
Shares used in calculating basic and diluted net loss per share	64,947	62,526	63,678	63,202