Accumulated Other Comprehensive Earnings (Loss): (Components AOCI) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 27, 2014
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	$ 690,809
Balance at the end of the period	693,111	$ 691,013
AOCI from Derivatives | Foreign currency forward contracts
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(1,236)	(436)
Other comprehensive earnings (loss) before reclassifications	(1,769)	(752)
Reclassifications from accumulated other comprehensive loss	1,106	398
Other comprehensive earnings (loss) net of tax	(663)	(354)
Balance at the end of the period	(1,899)	(790)
AOCI from Derivatives | Commodity futures contracts
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(470)	(96)
Other comprehensive earnings (loss) before reclassifications	(1,125)	(332)
Reclassifications from accumulated other comprehensive loss	1,000	188
Other comprehensive earnings (loss) net of tax	(125)	(144)
Balance at the end of the period	(595)	(240)
Investments
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(332)	54
Other comprehensive earnings (loss) before reclassifications	69	(202)
Other comprehensive earnings (loss) net of tax	69	(202)
Balance at the end of the period	(263)	(148)
Postretirement and Pension Benefits
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	6,439	9,367
Reclassifications from accumulated other comprehensive loss	(694)	(864)
Other comprehensive earnings (loss) net of tax	(694)	(864)
Balance at the end of the period	5,745	8,503
Foreign Currency Translation
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(17,499)	(13,527)
Other comprehensive earnings (loss) before reclassifications	(3,706)	(1,703)
Other comprehensive earnings (loss) net of tax	(3,706)	(1,703)
Balance at the end of the period	(21,205)	(15,230)
Accumulated Other Comprehensive Earnings ( Loss )
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(13,098)	(4,638)
Other comprehensive earnings (loss) before reclassifications	(6,531)	(2,989)
Reclassifications from accumulated other comprehensive loss	1,412	(278)
Other comprehensive earnings (loss) net of tax	(5,119)	(3,267)
Balance at the end of the period	$ (18,217)	$ (7,905)