Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
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)	0	7,000
Preferred stock, shares outstanding (in shares)	0	7,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	49,410,176	33,859,034
Common stock, shares outstanding (in shares)	49,376,843	33,825,701
Common stock, shares to be issued (in shares)		2,470,566
Treasury stock, at cost, shares (in shares)	33,333	33,333