Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 303,499	$ 289,125
Less accumulated depreciation	214,394	199,476
Total property, plant and equipment, net	89,105	89,649
Depreciation expense	17,800	17,400	$ 16,100
Land, Buildings and Improvements [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	38,833	38,299
Machinery and Equipment [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	148,578	142,531
Tools, Dies and Auxiliary Equipment [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	60,102	54,843
Furniture and Fixtures [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	30,347	30,470
Leasehold Improvements [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	11,948	11,711
Construction-in-Progress [Member]
Property, plant and equipment [Abstract]
Total property, plant and equipment	$ 13,691	$ 11,271