Retirement Plans - Net Pension Income or Postretirement Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Pension Plans
Net pension expense (income)
(Income) expense, net	$ (532)	$ (637)	$ (1,591)	$ (1,717)
Domestic Pension Plans
Net pension expense (income)
Service cost	42	48	128	144
Interest cost	2,815	3,052	8,444	9,163
Expected return on plan assets	(5,068)	(5,209)	(15,204)	(15,625)
Amortization of loss (gain)	1,585	1,408	4,754	4,237
Other cost due to retirement				172
(Income) expense, net	(626)	(701)	(1,878)	(1,909)
Foreign Pension Plans
Net pension expense (income)
Service cost	16	21	49	63
Interest cost	124	156	371	461
Expected return on plan assets	(135)	(172)	(402)	(509)
Amortization of loss (gain)	89	59	269	177
(Income) expense, net	94	64	287	192
Other Postretirement Benefit Plan
Net pension expense (income)
Service cost	1	1	3	3
Interest cost	51	57	153	172
Amortization of loss (gain)	(25)	(39)	(75)	(118)
(Income) expense, net	$ 27	$ 19	$ 81	$ 57