Goodwill and Other Intangible Assets Acquisition information (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 29, 2015	Mar. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Jan. 09, 2015	Feb. 05, 2014
Business Acquisition [Line Items]
Goodwill	$ 166,923,000	$ 184,260,000	$ 170,773,000	$ 136,152,000
Eisenberg [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	5,400,000
Business Acquisition, Transaction Costs	200,000
Net tangible assets assumed					100,000
Goodwill					4,100,000
Lithicon AS [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired						100.00%
Business Combination, Consideration Transferred		68,000,000
Business Acquisition, Transaction Costs			400,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred			400,000
Net tangible assets assumed						7,700,000
Goodwill						46,900,000
Net intangible assets acquired, fair value						22,000,000
Deferred Tax Assets, Goodwill and Intangible Assets						8,100,000
Developed technology [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, weighted average amortization period	10 years
Net intangible assets acquired, fair value						18,600,000
Customer relationships [Member] | Eisenberg [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, weighted average amortization period	5 years
Net intangible assets acquired, fair value					1,400,000
Customer relationships [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, weighted average amortization period	5 years
Net intangible assets acquired, fair value						2,200,000
Order or Production Backlog [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, weighted average amortization period	2 years
Net intangible assets acquired, fair value						$ 1,200,000