Debt (Financing Liability) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014	Dec. 28, 2014
Debt Instrument [Line Items]
Financing liability	$ 31,349		$ 31,349		$ 33,094
Other operating income	132	$ 0	493	$ 0
Financing Agreement June 2011 | SPAIN
Debt Instrument [Line Items]
Financing liability	$ 31,300		$ 31,300		$ 33,100
Financing arrangement, imputed interest on financing liability	6.365%		6.365%
Financing arrangement, interest expense recognized	$ 500	$ 600	$ 1,000	$ 1,100