Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Allowance for doubtful accounts	$ 118	$ 89
Accumulated depreciation and amortization	$ 20,867	$ 19,659
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)	6,294	6,257
Common stock, shares outstanding (in shares)	5,626	5,589
Treasury stock, shares (in shares)	668	668