Shareholders' Equity and Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 28, 2014		Mar. 29, 2013		Dec. 31, 2013		Dec. 31, 2012
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation	$ (14,514)		$ (21,029)		$ (14,219)		$ (16,515)
Net gain/(loss) on foreign currency translation	(295)		(4,514)
Reclassification to net income, foreign currency translation	0		0
Other Comprehensive Income (Loss), Foreign Currency Translation	(295)		(4,514)
Changes in pension and post-retirement benefit plans	(65,653)	[1]	(103,076)	[1]	(66,317)	[1]	(104,551)	[1]
Amortization of prior service cost, net of tax expense of $10 and $10, respectively	15	[1]	15	[1]
Amortization of net loss, net of tax expense of $392 and $894, respectively	649	[1]	1,460	[1]
Pension plan adjustments, net of tax expense	664	[1]	1,475	[1]
Accumulated Other Comprehensive Income (Loss), Unrealized Gain (Loss) on derivative instruments, Effect Net of Tax	(516)	[2]	(635)	[2]	(585)	[2]	(524)	[2]
Net loss on derivative instruments, net of tax expense (benefit) of $44 and $(68), respectively	(41)	[2]	(111)	[2]
Reclassification to net income, derivative instruments, net of tax benefit of $35	110	[2]	0	[2]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	69	[2]	(111)	[2]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(80,683)		(124,740)		(81,121)
Tax expense for pension plan adjustments	402		904
Tax expense (benefit) for the change in unrealized loss on derivative instruments	44		(68)
Tax expense (benefit) on loss on derivative instruments reclassified to net income	(35)
Amortization of prior service cost
Schedule of Accumulated Other Comprehensive Income [Line Items]
Tax expense for pension plan adjustments	10		10
Amortization of net loss
Schedule of Accumulated Other Comprehensive Income [Line Items]
Tax expense for pension plan adjustments	$ 392		$ 894

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension cost. (See Note 8, Pension Plans for additional information.)

[2] See Note 5, Derivative Financial Instruments, for additional information regarding our derivative instruments.