Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Pension Benefits | U.S.
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 0		$ 0
Interest Cost		283		850
Expected Return on Plan Assets		(248)		(745)
Recognized Net Actuarial Loss		8		24
Amortization of Prior Service Cost		0		0
Net periodic benefit cost		$ 43		$ 129
The weighted average assumptions used to determine net periodic benefit cost are as follows:
Discount Rate (as a percentage)		4.10%		4.10%
Expected Long-Term Return on Plan Assets (as a percentage)		4.10%		4.10%
Rate of Compensation Increase (as a percentage)		0.00%		0.00%
Pension Benefits | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 45	$ 43	$ 131	$ 129
Interest Cost	22	27	66	84
Expected Return on Plan Assets	(14)	(16)	(45)	(50)
Recognized Net Actuarial Loss	10	5	31	15
Amortization of Prior Service Cost	2	0	5	0
Net periodic benefit cost	$ 65	$ 59	$ 188	$ 178
The weighted average assumptions used to determine net periodic benefit cost are as follows:
Discount Rate (as a percentage)	2.05%	2.82%	2.12%	2.81%
Expected Long-Term Return on Plan Assets (as a percentage)	7.21%	9.22%	7.21%	9.22%
Rate of Compensation Increase (as a percentage)	3.14%	2.99%	3.17%	2.99%
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 2	$ 1	$ 5	$ 3
Interest Cost	9	37	29	112
Expected Return on Plan Assets	(1)	(1)	(3)	(3)
Recognized Net Actuarial Loss	4	3	12	9
Amortization of Prior Service Cost	0	0	0	0
Net periodic benefit cost	$ 14	$ 40	$ 43	$ 121
The weighted average assumptions used to determine net periodic benefit cost are as follows:
Discount Rate (as a percentage)	3.80%	4.44%	3.83%	4.44%
Expected Long-Term Return on Plan Assets (as a percentage)	7.21%	9.22%	7.21%	9.22%
Rate of Compensation Increase (as a percentage)	5.57%	5.57%	5.57%	5.57%