Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net revenues	$ 36,747us-gaap_SalesRevenueNet	$ 54,844us-gaap_SalesRevenueNet	$ 127,964us-gaap_SalesRevenueNet	$ 164,379us-gaap_SalesRevenueNet
Cost of revenues	14,842us-gaap_CostOfRevenue	21,644us-gaap_CostOfRevenue	52,815us-gaap_CostOfRevenue	65,383us-gaap_CostOfRevenue
Gross profit	21,905us-gaap_GrossProfit	33,200us-gaap_GrossProfit	75,149us-gaap_GrossProfit	98,996us-gaap_GrossProfit
Operating expenses:
Research and development	24,721us-gaap_ResearchAndDevelopmentExpense	29,870us-gaap_ResearchAndDevelopmentExpense	82,636us-gaap_ResearchAndDevelopmentExpense	120,926us-gaap_ResearchAndDevelopmentExpense
Selling, general and administrative	8,707	10,930	25,684	29,602
Gain on sale of TPack	0	0	0	(19,699)
Amortization of purchased intangible assets	0us-gaap_AdjustmentForAmortization	62us-gaap_AdjustmentForAmortization	105us-gaap_AdjustmentForAmortization	254us-gaap_AdjustmentForAmortization
Restructuring	221us-gaap_RestructuringCharges	38us-gaap_RestructuringCharges	1,322us-gaap_RestructuringCharges	1,130us-gaap_RestructuringCharges
Total operating expenses	33,649us-gaap_OperatingExpenses	40,900us-gaap_OperatingExpenses	109,747us-gaap_OperatingExpenses	132,213us-gaap_OperatingExpenses
Operating loss	(11,744)us-gaap_OperatingIncomeLoss	(7,700)us-gaap_OperatingIncomeLoss	(34,598)us-gaap_OperatingIncomeLoss	(33,217)us-gaap_OperatingIncomeLoss
Interest income, net	485us-gaap_InvestmentIncomeNonoperating	525us-gaap_InvestmentIncomeNonoperating	1,214us-gaap_InvestmentIncomeNonoperating	4,679us-gaap_InvestmentIncomeNonoperating
Other (expense) income, net	(10)us-gaap_OtherNonoperatingIncomeExpense	92us-gaap_OtherNonoperatingIncomeExpense	(2,536)us-gaap_OtherNonoperatingIncomeExpense	309us-gaap_OtherNonoperatingIncomeExpense
Loss before income taxes	(11,269)	(7,083)	(35,920)	(28,229)
Income tax expense	862us-gaap_IncomeTaxExpenseBenefit	201us-gaap_IncomeTaxExpenseBenefit	993us-gaap_IncomeTaxExpenseBenefit	581us-gaap_IncomeTaxExpenseBenefit
Net loss	$ (12,131)us-gaap_NetIncomeLoss	$ (7,284)us-gaap_NetIncomeLoss	$ (36,913)us-gaap_NetIncomeLoss	$ (28,810)us-gaap_NetIncomeLoss
Basic and diluted net loss per share (in Dollars per share)	$ (0.15)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.10)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.47)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.40)us-gaap_EarningsPerShareBasicAndDiluted
Shares used in calculating basic and diluted net loss per share (in Shares)	78,920	73,989	78,442	71,986

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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