Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Jun. 29, 2019	Jun. 30, 2018	Sep. 28, 2019	Sep. 29, 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					(25,609)
Tax effect					0
Other comprehensive income before reclassifications, net of tax					(25,609)
Amounts reclassified out of AOCI					6,136
Tax effect					(1,688)
Amounts reclassified out of AOCI, net of tax					4,448
Net other comprehensive income	$ (21,636)	$ 5,947	475	$ (31,331)	(21,161)	$ (25,384)
Ending Balance	(27,952)				(27,952)
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					6,136
Tax effect					(1,688)
Amounts reclassified out of AOCI, net of tax					4,448
Net other comprehensive income					4,448
Ending Balance	(53,843)				(53,843)
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					(25,609)
Tax effect					0
Other comprehensive income before reclassifications, net of tax					(25,609)
Amounts reclassified out of AOCI					0
Tax effect					0
Amounts reclassified out of AOCI, net of tax					0
Net other comprehensive income					(25,609)
Ending Balance	25,891				25,891
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	(21,636)	$ 5,947	$ 475	$ (31,331)
Ending Balance	$ (27,952)				$ (27,952)