Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 202,293	$ 180,041
Less: Accumulated depreciation	(125,629)	(113,412)
Property, plant and equipment, net	76,664	66,629
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	9,920	9,063
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 82,412	75,610
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	5 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	20 years
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 83,445	71,028
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	10 years
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 8,153	7,165
Office furniture and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Office furniture and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	7 years
Computer software
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 12,500	11,889
Computer software | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Computer software | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	7 years
Transportation equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 5,863	$ 5,286
Useful Lives	3 years