Retirement Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012
Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 415,000	$ 0	$ 1,449,000
Interest cost	3,421,000	3,642,000	10,263,000	10,908,000
Expected return on plan assets	(4,618,000)	(4,141,000)	(13,854,000)	(12,657,000)
Net amortization and deferral	(2,000)	(1,000)	(6,000)	(3,000)
Actuarial (gain) loss	1,992,000	1,562,000	5,976,000	4,818,000
Net periodic cost	793,000	1,477,000	2,379,000	4,515,000
Employer contributions			12,400,000
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	3,700,000		3,700,000
Reconciliation of Benefit Obligation [Roll Forward]
Service cost	0	415,000	0	1,449,000
Interest cost	3,421,000	3,642,000	10,263,000	10,908,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net Periodic Benefit Cost [Abstract]
Interest cost	200,000	200,000	600,000	700,000
Reconciliation of Benefit Obligation [Roll Forward]
Interest cost	$ 200,000	$ 200,000	$ 600,000	$ 700,000