Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	7,000	7,000
Preferred stock, shares outstanding (in shares)	7,000	7,000
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, shares issued (in shares)	33,660,970	33,191,571
Common stock, shares to be issued (in shares)	1,912,503	1,401,247
Common stock, shares outstanding (in shares)	33,627,637	33,158,238
Treasury stock, at cost, shares (in shares)	33,333	33,333