Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Real estate, accumulated depreciation	$ 2,886,259	$ 2,717,114
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	7,054,000	7,054,000
Preferred stock, shares issued (in shares)	19,580	19,580
Preferred stock, shares outstanding (in shares)	19,580	19,580
Preferred stock, liquidation preference	$ 489,500	$ 489,500
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	616,413,920	432,518,743
Common stock, shares outstanding (in shares)	616,413,920	432,518,743