Employee Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Pension benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 339	$ 230	$ 1,016	$ 691
Interest cost	2,185	2,343	6,556	7,028
Expected return on plan assets	(2,721)	(2,786)	(8,165)	(8,357)
Amortization of prior service cost (credit)	1	1	1	2
Amortization of net (gain)	966	587	2,900	1,760
Net periodic benefit cost	770	375	2,308	1,124
Other benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	67	75	200	226
Interest cost	278	309	835	928
Amortization of prior service cost (credit)	0	(1)	(1)	(2)
Amortization of net (gain)	(7)	(2)	(20)	(8)
Net periodic benefit cost	$ 338	$ 381	$ 1,014	$ 1,144