CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 490	$ 1,088
Preferred stock, par value (in dollars per share)	$ 0.05	$ 0.05
Preferred stock, shares authorized	4,000,000	4,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.05	$ 0.05
Common stock, shares authorized	25,000,000	25,000,000
Common stock, shares outstanding	14,896,043	14,782,018
Treasury stock, shares	82,136	39,783