Pensions and Other Postretirement Benefits (Components of Net Periodic Cost of Pension and Other Postretirement Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 738	$ 643	$ 1,682
Pension Plans | United States
Defined Benefit Plan Disclosure [Line Items]
Annual service cost	0	0	0
Less: employee contributions	0	0	0
Net service cost	0	0	0
Interest cost	70	85	76
Expected return on plan assets	0	0	0
Amortization of actuarial losses	109	38	70
Amortization of transition obligation	0	0	0
Curtailment and settlement losses	0	0	0
Net periodic benefit cost	179	123	146
Pension Plans | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Annual service cost	402	336	498
Less: employee contributions	0	0	21
Net service cost	402	336	477
Interest cost	442	535	610
Expected return on plan assets	(442)	(517)	(549)
Amortization of actuarial losses	286	164	437
Amortization of transition obligation	5	1	1
Curtailment and settlement losses	0	0	708
Net periodic benefit cost	693	519	1,684
OPEB Plans
Defined Benefit Plan Disclosure [Line Items]
Less: employee contributions	25	0
Net service cost	123	126	108
Interest cost	133	180	152
Amortization of actuarial losses	137	156	177
Net periodic benefit cost	$ 393	$ 462	$ 437