Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares shares in Thousands	Sep. 30, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	1,000	1,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	49,000	49,000
Common stock, shares issued (in shares)	18,500	17,520
Common stock, shares outstanding (in shares)	17,541	16,743
Treasury stock, shares (in shares)	959	777