Note 10 - Variable Interest Entities ("VIE") (Details Textual) $ in Thousands		Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Assets, Total	[1]	$ 11,614,498	$ 10,997,867
Liabilities, Total	[2]	$ 5,928,460	$ 6,051,017
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Number of Entities		22	23
Consolidated Operating Properties [Member]
Variable Interest Entity, Number of Entities		22	22
Consolidated Operating Properties [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Total		$ 1,000,000	$ 900,000
Liabilities, Total		$ 62,100	$ 70,900
Real Estate Under Development [Member]
Variable Interest Entity, Number of Entities			1
Real Estate Under Development [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Total			$ 346,900
Liabilities, Total			$ 82,500

[1] Includes restricted assets of consolidated variable interest entities ("VIEs") at December 31, 2020 and December 31, 2019 of $102,482 and $245,489, respectively. See Footnote 10 of the Notes to Consolidated Financial Statements.

[2] Includes non-recourse liabilities of consolidated VIEs at December 31, 2020 and December 31, 2019 of $62,076 and $153,436, respectively. See Footnote 10 of the Notes to Consolidated Financial Statements.