Employee Benefit Plans (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
Components of net periodic benefit costs:
Service cost	$ 516	$ 381	$ 1,548	$ 1,143
Interest cost	2,201	2,274	6,603	6,822
Expected return on plan assets	(1,509)	(1,656)	(4,527)	(4,968)
Amortization of unrecognized net loss	951	858	2,853	2,574
Amortization of prior service cost	11	11	33	33
Net periodic benefit costs	$ 2,170	$ 1,868	$ 6,510	$ 5,604