Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 29, 2019	Mar. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 29, 2019	Jun. 30, 2018
Cumulative balance of each component of other comprehensive income (loss) and income tax effects [Roll Forward]
Beginning Balance		$ (6,791)			$ (6,791)
Other comprehensive income before reclassifications					(2,605)
Tax effect					0
Other comprehensive income before reclassifications, net of tax					(2,605)
Amounts reclassified out of AOCI					4,107
Tax effect					(1,027)
Amounts reclassified out of AOCI, net of tax					3,080
Net other comprehensive income	$ 9,007	(8,532)	$ (59,962)	$ 28,631	475	$ (31,331)
Ending Balance	(6,316)				(6,316)
Pension and Other Post-Retirement Actuarial Items [Member]
Cumulative balance of each component of other comprehensive income (loss) and income tax effects [Roll Forward]
Beginning Balance		(58,291)			(58,291)
Other comprehensive income before reclassifications					0
Tax effect					0
Other comprehensive income before reclassifications, net of tax					0
Amounts reclassified out of AOCI					4,107
Tax effect					(1,027)
Amounts reclassified out of AOCI, net of tax					3,080
Net other comprehensive income					3,080
Ending Balance	(55,211)				(55,211)
Currency Translation Adjustment [Member]
Cumulative balance of each component of other comprehensive income (loss) and income tax effects [Roll Forward]
Beginning Balance		51,500			51,500
Other comprehensive income before reclassifications					(2,605)
Tax effect					0
Other comprehensive income before reclassifications, net of tax					(2,605)
Amounts reclassified out of AOCI					0
Tax effect					0
Amounts reclassified out of AOCI, net of tax					0
Net other comprehensive income					(2,605)
Ending Balance	48,895				48,895
Accumulated Other Comprehensive Income (Loss) [Member]
Cumulative balance of each component of other comprehensive income (loss) and income tax effects [Roll Forward]
Beginning Balance		(6,791)			(6,791)
Net other comprehensive income	9,007	$ (8,532)	$ (59,962)	$ 28,631
Ending Balance	$ (6,316)				$ (6,316)