Segment Information Income (Loss) by Segment and Reconciliation to Income Before Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 26, 2015	Apr. 27, 2014
Segment Reporting Information [Line Items]
Operating income	$ 4,884us-gaap_OperatingIncomeLoss	$ 11,149us-gaap_OperatingIncomeLoss
Items to reconcile segment operating income to consolidated income before taxes
Stock-based compensation expense	5,946	6,847
Restructuring charge	0us-gaap_RestructuringCharges	1,001us-gaap_RestructuringCharges
Interest expense, net	1,834us-gaap_InterestExpenseDebt	1,387us-gaap_InterestExpenseDebt
Non-operating (income) expense, net	493us-gaap_OtherNonoperatingIncomeExpense	278us-gaap_OtherNonoperatingIncomeExpense
Income before taxes	2,557	9,484
Corporate, Non-Segment [Member]
Items to reconcile segment operating income to consolidated income before taxes
Intangible amortization and impairments	6,163	6,425
Stock-based compensation expense	5,946	6,847
Inventory write-down	0	1,052
Restructuring charge	0	1,001
Environmental reserve	2,335	0
Other non-segment related expenses	3,200	444
Amortization of fair value adjustments related to acquired PP&E	548	339
Interest expense, net	1,834	1,387
Non-operating (income) expense, net	493	278
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	23,076	27,257
Semiconductor Products Group [Member]
Segment Reporting Information [Line Items]
Operating income	25,327	29,962
All others [Member]
Segment Reporting Information [Line Items]
Operating income	$ (2,251)	$ (2,705)

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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