Shareholders' Equity and Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 27, 2014		Jun. 28, 2013		Jun. 27, 2014		Jun. 28, 2013		Mar. 28, 2014		Dec. 31, 2013		Mar. 29, 2013	Dec. 31, 2012
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation	$ (12,759)		$ (21,273)		$ (12,759)		$ (21,273)		$ (14,514)		$ (14,219)		$ (21,029)	$ (16,515)
Foreign currency translation adjustments	1,755		(244)		1,460		(4,758)
Reclassification to net income, foreign currency translation	0				0		0
Other Comprehensive Income (Loss), Foreign Currency Translation	1,755		(244)		1,460		(4,758)
Changes in pension and post-retirement benefit plans	(64,980)	[1]	(101,600)	[1]	(64,980)	[1]	(101,600)	[1]	(65,653)	[1]	(66,317)	[1]	103,076	104,551
Amortization of prior service cost, net of tax expense of $10 and $10, respectively	13	[1]	15	[1]	28	[1]	30	[1]
Amortization of net loss, net of tax expense of $392 and $894, respectively	660	[1]	1,461	[1]	1,309	[1]	2,921	[1]
Pension plan adjustments, net of tax expense	673	[1]	1,476	[1]	1,337	[1]	2,951	[1]
Accumulated Other Comprehensive Income (Loss), Unrealized Gain (Loss) on derivative instruments, Effect Net of Tax	(516)	[2]	(463)	[2]	(516)	[2]	(463)	[2]	(516)	[2]	(585)	[2]	(635)	(524)	[2]
Net loss on derivative instruments, net of tax expense (benefit) of $44 and $(68), respectively	(88)	[2]	172	[2]	(129)	[2]	61	[2]
Reclassification to net income, derivative instruments, net of tax benefit of $35	88	[2]			198	[2]	0	[2]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	0	[2]	172	[2]	69	[2]	61	[2]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(78,255)		(123,336)		(78,255)		(123,336)				(81,121)
Tax expense for pension plan adjustments	408		904		810		1,810
Tax expense (benefit) for the change in unrealized loss on derivative instruments	(122)		105		(78)		38
Tax expense (benefit) on loss on derivative instruments reclassified to net income	84		0		119		0
Amortization of prior service cost
Schedule of Accumulated Other Comprehensive Income [Line Items]
Tax expense for pension plan adjustments	7		10		17		20
Amortization of net loss
Schedule of Accumulated Other Comprehensive Income [Line Items]
Tax expense for pension plan adjustments	$ 401		$ 894		$ 793		$ 1,790

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension cost. (See Note 10, Pension Plans for additional information.)

[2] See Note 7, Derivative Financial Instruments, for additional information regarding our derivative instruments.