Retirement Plans (Schedule of Net Periodic (Benefit) Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 1	$ 1
Interest cost	3,505	3,707	10,553	11,120
Expected return on plan assets	(5,280)	(5,206)	(15,732)	(15,618)
Net amortization and deferral	0	0	0	0
Net amortization and deferral	2,339	794	6,651	2,381
Net periodic expense (benefit)	$ 564	$ (705)	$ 1,473	$ (2,116)