Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 71	$ 64
Accumulated amortization and depreciation	$ 13,712	$ 11,670
Preferred stock, par value (in dollars per share)	$ 0.005	$ 0.005
Preferred stock, shares authorized (in shares)	873,000	873,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.005	$ 0.005
Common stock, shares authorized (in shares)	50,000	50,000
Common stock, shares issued (in shares)	6,175	6,160
Common stock, shares outstanding (in shares)	5,507	5,492
Treasury stock, shares (in shares)	668,000	668,000