Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Allowance for doubtful accounts	$ 65	$ 94
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	110,000,000	110,000,000
Common stock, shares issued (in shares)	30,898,600	30,898,600
Common stock, shares outstanding (in shares)	24,767,118	25,361,409
Treasury stock, shares (in shares)	6,131,482	5,537,191