Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 29, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2015	$ (71,016)
Other comprehensive (loss) income	3,637	$ (6,335)
Balance at March 31, 2016	(67,379)
Unrecognized Benefit Plan Gains and Losses
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2015	(57,391)
Other comprehensive (loss) income	(58)
Balance at March 31, 2016	(57,449)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2015	(15,764)
Other comprehensive (loss) income	4,043
Balance at March 31, 2016	(11,721)
Unrealized Holding Gain on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at December 31, 2015	2,139
Other comprehensive (loss) income	(348)
Balance at March 31, 2016	$ 1,791