Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Parentheticals) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized loss on interest rate swaps, net of tax of $1,016	$ (469)	$ 415	$ (1,016)	$ (206)
Reclassification of loss into earnings from interest rate swaps, net of tax of $222	110	50	222	101
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net of tax of $8	(4)	(4)	(8)	(8)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $1	$ 0	$ (9)	(1)	$ (19)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized loss on interest rate swaps, net of tax of $1,016			(1,016)
Reclassification of loss into earnings from interest rate swaps, net of tax of $222			222
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net of tax of $8			(8)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $1			$ (1)