Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2016	$ (619)
Other comprehensive loss before reclassifications	(13)
Amounts reclassified from accumulated OCI	(150)
Net other comprehensive loss	(163)	$ 368
Balance as of April 1, 2017	(782)
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2016	(326)
Other comprehensive loss before reclassifications	(13)
Amounts reclassified from accumulated OCI	0
Net other comprehensive loss	(13)
Balance as of April 1, 2017	(339)
Post Retirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2016	(293)
Other comprehensive loss before reclassifications	0
Amounts reclassified from accumulated OCI	(150)
Net other comprehensive loss	(150)
Balance as of April 1, 2017	$ (443)