Property, Plant, and Equipment - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, plant, and equipment
Gross property, plant and equipment	$ 215,090	$ 211,340
Less: accumulated depreciation and amortization	149,819	135,629
Net property, plant, and equipment	65,271	75,711	$ 80,284
Depreciation expense	15,400	17,300	$ 17,600
Proceeds from sale of land		600
Land
Property, plant, and equipment
Gross property, plant and equipment	5,061	5,061
Building and improvements
Property, plant, and equipment
Gross property, plant and equipment	$ 62,865	61,884
Building and improvements | Minimum
Property, plant, and equipment
Average Useful Life	10 years
Building and improvements | Maximum
Property, plant, and equipment
Average Useful Life	40 years
Machinery and equipment
Property, plant, and equipment
Gross property, plant and equipment	$ 140,493	137,692
Machinery and equipment | Minimum
Property, plant, and equipment
Average Useful Life	3 years
Machinery and equipment | Maximum
Property, plant, and equipment
Average Useful Life	10 years
Leaseholds improvements
Property, plant, and equipment
Gross property, plant and equipment	$ 6,671	$ 6,703
Leaseholds improvements | Minimum
Property, plant, and equipment
Average Useful Life	3 years
Leaseholds improvements | Maximum
Property, plant, and equipment
Average Useful Life	7 years