Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Real estate, accumulated depreciation	$ 2,474,243	$ 2,385,287
Assets of consolidated variable interest entities	229,716	239,012
Liabilities of consolidated variable interest entities	$ 149,529	$ 143,186
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)	28,580	42,580
Preferred stock, shares outstanding (in shares)	28,580	42,580
Preferred stock, liquidation preference	$ 714,500	$ 1,064,500
Preferred stock, undesignated (in shares)	6,010,240	5,996,240
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)	422,230,015	421,388,879
Common stock, shares outstanding (in shares)	422,230,015	421,388,879