Accumulated Other Comprehensive Income (Loss) (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss - total	$ (808)	$ (108)	$ (1,299)
Unrealized gain (loss) on interest rate swaps	(1,316)	(1,109)	531
Reclassification of loss into earnings from interest rate swaps	1,624	444	673
Unrecognized net actuarial gain on postretirement benefit plans	0	(6)	18
Reclassification of net actuarial gain into earnings from postretirement benefit plans	(27)	(27)	(27)
Reclassification of prior service credits into earnings from postretirement benefit plans	(3)	(2)	(4)
Accumulated other comprehensive loss - total	(530)	(808)	(108)
Income taxes	0	0	0
Income taxes	343	10	0
Income taxes	0	0	0
Income taxes	0	0	0
Income taxes	0	0	0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss - total	(1,048)	(383)	(1,587)
Unrealized gain (loss) on interest rate swaps	(1,316)	(1,109)	531
Reclassification of loss into earnings from interest rate swaps	1,624	444	673
Accumulated other comprehensive loss - total	(740)	(1,048)	(383)
Income taxes	0	0	0
Income taxes	343	10	0
Income taxes	0	0	0
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss - total	240	275	288
Unrecognized net actuarial gain on postretirement benefit plans		(6)	18
Reclassification of net actuarial gain into earnings from postretirement benefit plans	(27)	(27)	(27)
Reclassification of prior service credits into earnings from postretirement benefit plans	(3)	(2)	(4)
Accumulated other comprehensive loss - total	210	240	275
Income taxes	0	0	0
Income taxes	0	0	0
Income taxes	$ 0	$ 0	$ 0