Pension and Postretirement Benefit Plans Net Periodic Benefit (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012
Pension Plans
Components of net periodic benefit cost:
Service cost	$ 844	$ 495	$ 2,523	$ 1,509
Interest cost	1,387	1,417	4,157	4,288
Return on plan assets	(1,880)	(1,590)	(5,628)	(4,808)
Curtailment / settlement (gain) loss	0	0	0	38
Transition costs and other	87	(14)	262	(45)
Net periodic benefit cost	438	308	1,314	982
Postretirement Benefit Plans
Components of net periodic benefit cost:
Service cost	14	14	44	49
Interest cost	45	55	137	163
Curtailment / settlement (gain) loss	0	(4)	0	218
Transition costs and other	9	7	27	19
Net periodic benefit cost	$ 68	$ 72	$ 208	$ 449