Debt (Financing Liability) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014	Dec. 28, 2014
Debt Instrument [Line Items]
Current portion of financing liability	$ 6,139		$ 6,139		$ 0
Other operating income	0	$ 0	493	$ 0
Financing Agreement June 2011 | SPAIN
Debt Instrument [Line Items]
Financing liability	$ 31,900		$ 31,900		$ 33,100
Financing arrangement, imputed interest on financing liability	6.365%		6.365%
Financing arrangement, interest expense recognized	$ 500	$ 600	$ 1,500	$ 1,700