Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	56,902,140	20,691,301
Common stock, shares outstanding (in shares)	56,902,140	20,691,301
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Convertible Preferred Stock [Member]
Preferred stock, shares authorized (in shares)	7,937,057	0