Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowances	$ 6,236	$ 5,242
Property, plant and equipment, accumulated depreciation	151,502	147,553
Accumulated amortization on intangible assets	$ 8,808	$ 8,533
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares issued (in shares)	30,219,278	30,219,278
Common stock, shares outstanding (in shares)	30,219,278	30,219,278
Treasury stock, shares (in shares)	1,175,795	1,175,795