Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Accounts receivable, allowances	$ 5,262	$ 5,139
Property, plant and equipment, accumulated depreciation	146,931	143,781
Accumulated amortization on intangible assets	$ 9,899	$ 9,568
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)	30,512,843	30,512,843
Common stock, shares outstanding (in shares)	30,512,843	30,512,843
Treasury stock, shares (in shares)	1,334,251	1,334,251