Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands		Jun. 30, 2021	Dec. 31, 2020
Real estate, accumulated depreciation		$ 2,784,417	$ 2,717,114
Total assets	[1]	11,558,922	11,614,498
Total liabilities	[2]	$ 5,770,923	$ 5,928,460
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)		433,516,714	432,518,743
Common stock, shares outstanding (in shares)		433,516,714	432,518,743
Variable Interest Entity, Primary Beneficiary [Member] | Nonrecourse [Member]
Total liabilities		$ 60,700	$ 62,100
Variable Interest Entity, Primary Beneficiary [Member] | Asset Pledged as Collateral [Member]
Total assets		$ 101,800	$ 102,500

[1] Includes restricted assets of consolidated variable interest entities ("VIEs") at June 30, 2021 and December 31, 2020 of $101,807 and $102,482, respectively. See Footnote 11 of the Notes to Condensed Consolidated Financial Statements.

[2] Includes non-recourse liabilities of consolidated VIEs at June 30, 2021 and December 31, 2020 of $60,723 and $62,076, respectively. See Footnote 11 of the Notes to Condensed Consolidated Financial Statements.