Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) - total			$ (1,960)
Unrealized loss on interest rate swaps, net	$ (35)	$ 15	(223)	$ (1,642)
Reclassification of loss into earnings from interest rate swaps, net	178	191	601	552
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net	(5)	(6)	(15)	(18)
Reclassification of prior service credits into earnings from postretirement benefit plans, net	(1)	$ (1)	(2)	$ (2)
Accumulated other comprehensive income (loss) - total	(1,599)		(1,599)
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			(2,216)
Unrealized loss on interest rate swaps, net			(223)
Reclassification of loss into earnings from interest rate swaps, net			601
Accumulated other comprehensive income (loss) - total	(1,838)		(1,838)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) - total			256
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net			(15)
Reclassification of prior service credits into earnings from postretirement benefit plans, net			(2)
Accumulated other comprehensive income (loss) - total	$ 239		$ 239