CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 35	$ 34
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	28,371,000	28,194,000
Common stock, shares outstanding (in shares)	24,264,000	24,102,000
Treasury stock, shares (in shares)	4,107,000	4,092,000