Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 77	$ 64
Accumulated amortization and depreciation	$ 13,181	$ 11,670
Preferred stock, par value (in dollars per share)	$ 0.005	$ 0.005
Preferred stock, shares authorized (in shares)	873	873
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
Treasury stock, shares (in shares)	668	668

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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