Note 7 - Investment and Advances in Real Estate Joint Ventures - Investment and Advances to Real Estate Joint Ventures - Balance Sheets (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate Investment Property, Net, Total		$ 9,346,041	$ 9,209,053
Other Assets, Total		97,225	194,682
Assets, Total	[1]	11,614,498	10,997,867
Notes payable, net		5,044,208	4,831,759
Secured Debt, Total		311,272	484,008
Other Liabilities, Total		324,538	346,183
Members’ capital		5,608,044	4,864,892
Total Liabilities and Members' Capital		11,614,498	10,997,867
Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance		62,210	64,015
Members’ capital		5,670,254	4,928,907	$ 5,411,053	$ 5,530,245
KIR [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Real Estate Investment Property, Net, Total		787,100	788,700
Other Assets, Total		75,300	83,600
Assets, Total		862,400	872,300
Notes payable, net		91,500	0
Secured Debt, Total		445,400	556,000
Other Liabilities, Total		17,400	16,300
Members’ capital		308,100	300,000
Total Liabilities and Members' Capital		862,400	872,300
Excluding KIR [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Real Estate Investment Property, Net, Total		2,549,200	2,596,900
Other Assets, Total		179,000	140,300
Assets, Total		2,728,200	2,737,200
Notes payable, net		199,800	199,800
Secured Debt, Total		804,300	838,300
Other Liabilities, Total		53,600	59,500
Total Liabilities and Members' Capital		2,728,200	2,737,200
Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance		18,300	17,700
Members’ capital		$ 1,652,200	$ 1,621,900

[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.