Retirement Plans (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013
Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 1,000	$ 0
Interest cost	3,707,000	3,421,000	7,413,000	6,842,000
Expected return on plan assets	(5,206,000)	(4,618,000)	(10,412,000)	(9,236,000)
Net amortization and deferral	0	(2,000)	0	(4,000)
Net amortization and deferral	794,000	1,992,000	1,587,000	3,984,000
Net periodic (benefit) expense	(705,000)	793,000	(1,411,000)	1,586,000
Employer contributions			6,900,000
Estimated future employer contributions during 2014			11,200,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net Periodic Benefit Cost [Abstract]
Interest cost	$ 200,000	$ 200,000	$ 400,000	$ 400,000