Goodwill and Other Intangible Assets Acquisition information (Details) - USD ($) $ in Thousands			6 Months Ended
	Jan. 09, 2015	Feb. 05, 2014	Jun. 28, 2015	Dec. 31, 2014	Jun. 29, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill			$ 167,936	$ 170,773	$ 184,994	$ 136,152
Eisenberg [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 5,400
Business Acquisition, Transaction Costs	200
Net tangible assets assumed	100
Goodwill	4,100
Lithicon AS [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 68,000
Business Acquisition, Transaction Costs		400
Net tangible assets assumed		$ 7,700
Percentage of voting interests acquired		100.00%
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred		$ 400
Goodwill		46,900
Net intangible assets acquired, fair value		22,000
Deferred Tax Assets, Goodwill and Intangible Assets		8,100
Developed technology [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, fair value		18,600
Net intangible assets acquired, weighted average amortization period			10 years
Customer relationships [Member] | Eisenberg [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, fair value	$ 1,400
Net intangible assets acquired, weighted average amortization period			5 years
Customer relationships [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, fair value		2,200
Net intangible assets acquired, weighted average amortization period			5 years
Order or Production Backlog [Member] | Lithicon AS [Member]
Business Acquisition [Line Items]
Net intangible assets acquired, fair value		$ 1,200
Net intangible assets acquired, weighted average amortization period			2 years