Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Oct. 03, 2015	Oct. 01, 2016	Oct. 03, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2015			$ (1,199)
Other comprehensive income before reclassifications			331
Amounts reclassified from accumulated OCI			138
Net other comprehensive income	$ 46	$ 70	469	$ 216
Balance as of October 1, 2016	(730)		(730)
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2015			(378)
Other comprehensive income before reclassifications			331
Amounts reclassified from accumulated OCI			0
Net other comprehensive income			331
Balance as of October 1, 2016	(47)		(47)
Post Retirement Obligations
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2015			(821)
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated OCI			138
Net other comprehensive income			138
Balance as of October 1, 2016	$ (683)		$ (683)