Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Apr. 26, 2015	Apr. 27, 2014
Net sales	$ 130,088us-gaap_SalesRevenueNet	$ 132,859us-gaap_SalesRevenueNet
Cost of sales	51,688us-gaap_CostOfGoodsSold	54,775us-gaap_CostOfGoodsSold
Gross profit	78,400us-gaap_GrossProfit	78,084us-gaap_GrossProfit
Operating costs and expenses:
Selling, general and administrative	37,675	31,696
Product development and engineering	29,678us-gaap_ResearchAndDevelopmentExpense	27,813us-gaap_ResearchAndDevelopmentExpense
Intangible amortization	6,163us-gaap_AmortizationOfIntangibleAssets	6,425us-gaap_AmortizationOfIntangibleAssets
Restructuring charge	0us-gaap_RestructuringCharges	1,001us-gaap_RestructuringCharges
Total operating costs and expenses	73,516us-gaap_OperatingExpenses	66,935us-gaap_OperatingExpenses
Operating income	4,884us-gaap_OperatingIncomeLoss	11,149us-gaap_OperatingIncomeLoss
Interest expense, net	(1,834)us-gaap_InterestExpenseDebt	(1,387)us-gaap_InterestExpenseDebt
Non-operating expense, net	(493)us-gaap_OtherNonoperatingIncomeExpense	(278)us-gaap_OtherNonoperatingIncomeExpense
Income before taxes	2,557	9,484
Provision for taxes	2,699us-gaap_IncomeTaxExpenseBenefit	1,617us-gaap_IncomeTaxExpenseBenefit
Net (loss) income	$ (142)us-gaap_ProfitLoss	$ 7,867us-gaap_ProfitLoss
(Loss) earnings per share:
Basic (in dollars per share)	$ 0.00us-gaap_EarningsPerShareBasic	$ 0.12us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 0.00us-gaap_EarningsPerShareDiluted	$ 0.12us-gaap_EarningsPerShareDiluted
Weighted average number of shares used in computing earnings per share:
Basic (in shares)	66,713	67,300
Diluted (in shares)	66,713	67,970

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