Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
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
Real estate, accumulated depreciation		2,552,669	2,500,053
Total assets	[1]	11,305,134	10,997,867
Total liabilities	[2]	$ 6,414,722	$ 6,051,017
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)		432,525,409	431,814,951
Common stock, shares outstanding (in shares)		432,525,409	431,814,951
Variable Interest Entity, Primary Beneficiary [Member] | Nonrecourse [Member]
Total liabilities		$ 65,500	$ 153,400
Variable Interest Entity, Primary Beneficiary [Member] | Asset Pledged as Collateral [Member]
Total assets		$ 104,200	$ 245,500

[1] Includes restricted assets of consolidated variable interest entities ("VIEs") at March 31, 2020 and December 31, 2019 of $104,243 and $245,489, respectively. See Footnote 10 of the Notes to Condensed Consolidated Financial Statements.

[2] Includes non-recourse liabilities of consolidated VIEs at March 31, 2020 and December 31, 2019 of $65,544 and $153,436, respectively. See Footnote 10 of the Notes to Condensed Consolidated Financial Statements.