Pension and Other Postretirement Obligations (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2011	Jul. 04, 2010	Jul. 03, 2011	Jul. 04, 2010
Pension Obligations [Member]
Components of net periodic benefit costs for our pension plans
Service cost	$ 1,364	$ 1,304	$ 2,713	$ 3,164
Interest cost	2,867	3,031	5,678	7,257
Expected return on plan assets	(2,901)	(2,974)	(5,761)	(7,298)
Amortization of prior service cost	(36)	4	(72)	20
Net loss recognition	1,545	574	3,088	1,518
Net periodic benefit cost	2,839	1,939	5,646	4,661
Other Postretirement Obligations [Member]
Components of net periodic benefit costs for our pension plans
Service cost	41	25	81	50
Interest cost	672	632	1,353	1,258
Amortization of prior service cost	(59)	(54)	(119)	(107)
Net loss recognition	111	58	230	116
Net periodic benefit cost	$ 765	$ 661	$ 1,545	$ 1,317