General (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Dec. 28, 2017	Jun. 28, 2018	Jun. 29, 2017	Jun. 28, 2018		Jun. 29, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Interest Rate Swaps	$ 0			$ 0
Other comprehensive loss before reclassifications, Interest Rate Swaps		$ 169	$ 0	(1)		$ 0
Amounts reclassified from accumulated other comprehensive loss, Interest Rate Swaps	0	62	0	88	[1]	0
Net other comprehensive income, Interest Rate Swaps				87
Ending Balance, Interest Rate Swaps	0	87		87
Beginning Balance, Available for Sale Investments	(11)			0		3
Change in unrealized gain on available for sale investments, Available for Sale Investments		0	0	0		(14)
Other comprehensive loss before reclassifications, Available for Sale Investments				0
Amounts reclassified from accumulated other comprehensive loss, Available for Sale Investments	11			0	[1]
Net other comprehensive income, Available for Sale Investments				0		(14)
Ending Balance, Available for Sale Investments	0	0	(11)	0		(11)
Beginning Balance, Pension Obligation	(7,414)			(7,414)		(5,069)
Amortization of the net actuarial loss and prior service credit, Pension Obligation		113	53	227		107
Other comprehensive loss before reclassifications, Pension Obligation				0
Amounts reclassified from accumulated other comprehensive loss, Pension Obligation	0			0	[1]
Net other comprehensive income, Pension Obligation				227		107
Ending Balance, Pension Obligation	(7,414)	(7,187)	(4,962)	(7,187)		(4,962)
Beginning Balance, Accumulated Other Comprehensive Loss	(7,425)			(7,425)		(5,066)
Change In Unrealized Gain On Available For Sale Investments, Accumulated Other Comprehensive Loss						(14)
Amortization of net actuarial loss and prior service credit, Accumulated Other Comprehensive Loss		113	53	227		107
Other comprehensive loss before reclassifications, Accumulated Other Comprehensive Loss				(1)
Amounts reclassified from accumulated other comprehensive loss, Accumulated Other Comprehensive Loss	11			88	[1]
Net Other Comprehensive Income loss, Accumulated Other Comprehensive Loss				314		93
Ending Balance, Accumulated Other Comprehensive Loss	$ (7,425)	$ (7,100)	$ (4,973)	$ (7,100)		$ (4,973)

[1] Amount is included in interest expense in the consolidated statements of earnings.