Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Series B preferred stock, par value (in dollars per share)	$ 0.25	$ 0.25
Series B preferred stock, shares issued (in shares)	157,816	157,816
Series B preferred stock, shares outstanding (in shares)	157,816	157,816
Series B preferred stock, liquidation preference	$ 7,891	$ 7,891
Common stock, par value (in dollars per share)	$ 0.25	$ 0.25
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	544,217,951	538,487,415
Treasury stock, shares (in shares)	7,395,295	6,821,044