Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 621,592	$ 594,249
Finance lease assets	1,057	0
Less: accumulated depreciation	(417,182)	(404,629)
Property, plant and equipment, net	204,410	189,620
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,139	4,275
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	134,509	128,887
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	449,185	422,333
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 31,702	$ 38,753