Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property Plant And Equipment [Abstract]

Schedule of Property, Plant and Equipment

(Dollars in thousands)	Range of useful lives	2017			2016
Land		$	4,707		$	4,712
Buildings and improvements	10-40 years		55,734			54,448
Machinery and equipment	2-25 years		197,648			190,316
Construction in progress			1,348			1,437
			259,437			250,913
Less: accumulated depreciation			(182,208	)		(178,093	)
Total property, plant and equipment, net		$	77,229		$	72,820