Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Parentheticals) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 26, 2016	Mar. 28, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized loss on interest rate swaps, net of tax of $547	$ (547)	$ (621)
Reclassification of loss into earnings from interest rate swaps, net of tax of $112	112	51
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net of tax of $4	(4)	(4)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $0	0	$ (9)
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 $547	(547)
Reclassification of loss into earnings from interest rate swaps, net of tax of $112	112
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 $4	(4)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $0	$ 0