Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Parentheticals) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized loss on interest rate swaps, net of tax of $115	$ (136)	$ (469)	$ (115)	$ (1,016)
Reclassification of loss into earnings from interest rate swaps, net of tax of $260	123	110	260	222
Reclassification of net actuarial gain into earnings from postretirement benefit plans, net of tax of $6	(3)	(4)	(6)	(8)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $1	$ 0	$ 0	(1)	$ (1)
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 $115			(115)
Reclassification of loss into earnings from interest rate swaps, net of tax of $260			260
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 $6			(6)
Reclassification of prior service credits into earnings from postretirement benefit plans, net of tax of $1			$ (1)