Property, Plant and Equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) a	Dec. 31, 2017 USD ($)
Property, Plant and Equipment
Property, plant and equipment - gross	$ 188,655	$ 189,076
Less accumulated depreciation and amortization, including accumulated amortization of capitalized leases	101,798	(92,980)
Total property, plant and equipment, net	86,857	96,096
Depreciation	11,495	12,849
Proceeds from the sale of property, plant, and equipment	2,389	1,462
Land
Property, Plant and Equipment
Property, plant and equipment - gross	$ 12,440	14,869
Area of land (in acres) | a	54.5
Improvements to land and leaseholds
Property, Plant and Equipment
Property, plant and equipment - gross	$ 17,610	17,415
Buildings
Property, Plant and Equipment
Property, plant and equipment - gross	34,608	34,929
Machinery and equipment, including equipment under capitalized leases
Property, Plant and Equipment
Property, plant and equipment - gross	120,914	120,806
Construction in progress
Property, Plant and Equipment
Property, plant and equipment - gross	$ 3,083	$ 1,057