Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, Balance at December 28, 2014	$ (46,541)
Other comprehensive loss	(13,169)
Accumulated Other Comprehensive Income, Balance at June 30, 2015	(59,710)
Unrecognized Benefit Plan Gains and Losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, Balance at December 28, 2014	(49,323)
Other comprehensive loss	(662)
Accumulated Other Comprehensive Income, Balance at June 30, 2015	(49,985)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, Balance at December 28, 2014	(2,665)
Other comprehensive loss	(8,879)
Accumulated Other Comprehensive Income, Balance at June 30, 2015	(11,544)
Unrealized Holding Gains on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, Balance at December 28, 2014	5,447
Other comprehensive loss	(3,628)
Accumulated Other Comprehensive Income, Balance at June 30, 2015	$ 1,819