Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Domestic Plans
Net periodic benefit cost:
Service cost	$ 331	$ 323	$ 662	$ 645
Interest cost	806	788	1,612	1,576
Expected return on plan assets	(973)	(1,018)	(1,946)	(2,036)
Prior service cost	3	3	6	6
Cumulative actuarial net loss	104	0	208	0
Net periodic benefit cost	271	96	542	191
Foreign Plans
Net periodic benefit cost:
Service cost	649	606	1,290	1,197
Interest cost	802	924	1,593	1,827
Expected return on plan assets	(952)	(1,095)	(1,890)	(2,164)
Prior service cost	5	5	11	10
Cumulative actuarial net loss	60	14	119	28
Net periodic benefit cost	564	454	1,123	898
OPEB Plans
Net periodic benefit cost:
Service cost	2	3	6	6
Interest cost	44	49	87	98
Expected return on plan assets	0	0	0	0
Prior service cost	(2)	(2)	(4)	(4)
Cumulative actuarial net loss	(5)	(11)	(10)	(22)
Net periodic benefit cost	$ 39	$ 39	$ 79	$ 78