Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) - total			$ (808)
Unrealized gain on interest rate swaps, net	$ (139)	$ (705)	(1,276)	$ (1,104)
Reclassification of loss into earnings from interest rate swaps, net	365	93	573	139
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net	(6)	(7)	(13)	(14)
Reclassification of prior service credits into earnings from postretirement benefit plans, net	(1)	$ (1)	(2)	$ (2)
Accumulated other comprehensive income (loss) - total	(1,526)		(1,526)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) - total			(1,048)
Unrealized gain on interest rate swaps, net			(1,276)
Reclassification of loss into earnings from interest rate swaps, net			573
Accumulated other comprehensive income (loss) - total	(1,751)		(1,751)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) - total			240
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net			(13)
Reclassification of prior service credits into earnings from postretirement benefit plans, net			(2)
Accumulated other comprehensive income (loss) - total	$ 225		$ 225