Employee Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Apr. 02, 2011
Pension benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 360	$ 254
Interest cost	2,219	2,155
Expected return on plan assets	(2,713)	(2,652)
Amortization of prior service cost	0	0
Amortization of net loss (gain)	943	574
Net periodic benefit cost (income)	809	331
Other benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	75	69
Interest cost	309	318
Amortization of prior service cost	0	1
Amortization of net loss (gain)	3	25
Net periodic benefit cost (income)	$ 387	$ 413