CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful receivables	$ 1,507	$ 1,429
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, authorized (shares)	500,000	500,000
Preferred stock, issued (shares)	0	0
Preferred stock, outstanding (shares)	0	0
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, authorized (shares)	30,000,000	30,000,000
Common stock, issued (shares)	25,018,000	24,858,000
Treasury stock, shares (shares)	7,626,000	7,626,000