Retirement Plans - Net Pension Income or Postretirement Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Pension Plans
Net pension expense (income)
(Income) expense, net	$ (530)	$ (454)	$ (1,059)	$ (1,080)
Domestic Pension Plans
Net pension expense (income)
Service cost	42	48	86	96
Interest cost	2,815	3,053	5,629	6,111
Expected return on plan assets	(5,068)	(5,208)	(10,136)	(10,416)
Amortization of loss (gain)	1,585	1,416	3,169	2,829
Other cost due to retirement		172		172
(Income) expense, net	(626)	(519)	(1,252)	(1,208)
Foreign Pension Plans
Net pension expense (income)
Service cost	16	21	33	42
Interest cost	124	155	247	305
Expected return on plan assets	(134)	(170)	(267)	(337)
Amortization of loss (gain)	90	59	180	118
(Income) expense, net	96	65	193	128
Other Postretirement Benefit Plan
Net pension expense (income)
Service cost	1	1	2	2
Interest cost	51	58	102	115
Amortization of loss (gain)	(25)	(40)	(50)	(79)
(Income) expense, net	$ 27	$ 19	$ 54	$ 38