Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, issued (in shares)	23,003,109	22,265,971
Common stock, shares outstanding (in shares)	23,003,109	22,265,971