Pensions and Other Postretirement Benefit Plans (Schedule of Net Periodic Benefit Plan Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Curtailment (gain)/loss		$ (500)	$ (700)
Pension plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 2,279	2,543	2,723
Interest cost	6,172	7,216	7,217
Expected return on assets	(6,853)	(8,285)	(8,873)
Amortization of prior service cost/(credit)	14	68	34
Amortization of net actuarial loss	2,412	2,253	2,219
Settlement	148	(16)	2,246
Curtailment (gain)/loss	263	466	(752)
Net periodic benefit cost	$ 4,435	$ 4,245	$ 4,814
Pension plans | United States
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.40%	4.41%	3.70%
Expected return on plan assets	3.54%	4.57%	3.87%
Rate of compensation increase	0.00%	0.00%	0.00%
Pension plans | Foreign Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	2.31%	2.98%	2.83%
Expected return on plan assets	3.45%	4.45%	4.83%
Rate of compensation increase	2.81%	3.02%	3.04%
Pension plans | Switzerland
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Cash balance interest crediting rate	0.25%	850.00%	0.65%
Other postretirement benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 200	$ 189	$ 232
Interest cost	1,712	2,114	2,024
Expected return on assets	0	0	0
Amortization of prior service cost/(credit)	(4,488)	(4,488)	(4,488)
Amortization of net actuarial loss	2,592	2,227	2,956
Settlement	0	0	0
Curtailment (gain)/loss	0	0	0
Net periodic benefit cost	$ 16	$ 42	$ 724
Other postretirement benefits | United States
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.27%	4.31%	3.59%
Expected return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase		3.00%	0.00%
Other postretirement benefits | Foreign Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	3.05%	3.65%	3.40%
Expected return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	3.00%	3.00%	3.00%
Other postretirement benefits | Switzerland
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Cash balance interest crediting rate	0.00%	0.00%	0.00%