Goodwill and Other Intangible Assets Acquisition information (Details) - USD ($) $ in Thousands		9 Months Ended
	Jan. 09, 2015	Sep. 27, 2015	Dec. 31, 2014	Sep. 28, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill		$ 145,639	$ 170,773	$ 177,820	$ 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
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