Summary Of Significant Accounting Policies (Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014	Dec. 28, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
(Loss) earnings before income taxes	$ (2,012)	$ 10,035	$ (8,791)	$ 22,757
Income tax benefit (expense)	(1,979)	(14,110)	(7,251)	(17,107)
Net (loss) earnings	(3,991)	(4,075)	(16,042)	5,650	$ 10,953
Reclassification out of Accumulated Other Comprehensive Income [Member] | Amortization of pension plan items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Actuarial loss	(737)	(373)	(2,220)	(1,144)
Prior service cost	(7)	(3)	(20)	(9)
(Loss) earnings before income taxes	(744)	(376)	(2,240)	(1,153)
Income tax benefit (expense)	(425)	(217)	10	5
Net (loss) earnings	$ (1,169)	$ (593)	$ (2,230)	$ (1,148)