Property, Plant and Equipment, net - Schedule of components of property, plant and equipment, net, excluding discontinued operations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of property, plant and equipment [Abstract]
Property, plant and equipment, Gross	$ 30,304	$ 25,304
Less accumulated depreciation	(19,549)	(18,269)
Property, plant and equipment, Net	10,755	7,035
Land
Components of property, plant and equipment [Abstract]
Property, plant and equipment, Gross	253	253
Building and improvements
Components of property, plant and equipment [Abstract]
Property, plant and equipment, Gross	6,205	5,816
Rental property
Components of property, plant and equipment [Abstract]
Property, plant and equipment, Gross	5,650	5,345
Furniture and equipment
Components of property, plant and equipment [Abstract]
Property, plant and equipment, Gross	$ 18,196	$ 13,890