Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2022	Dec. 31, 2021
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,800,000	1,800,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	217,726,053	210,890,930
Common stock, shares outstanding (in shares)	217,726,053	210,890,930
Series A Preferred Stock [Member]
Preferred stock, shares authorized (in shares)	300,000	300,000
Preferred stock, shares issued (in shares)	138,557	141,873
Preferred stock, shares outstanding (in shares)	138,557	141,873
Series B Preferred Stock [Member]
Preferred stock, shares authorized (in shares)	1,500,000	1,500,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0