Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Apr. 02, 2011
Components of net periodic benefit costs:
Service cost	$ 516	$ 381
Interest cost	2,201	2,274
Expected return on plan assets	(1,509)	(1,656)
Amortization of unrecognized net loss	951	858
Amortization of prior service cost	11	11
Net periodic benefit costs	$ 2,170	$ 1,868