Note 4 - Investments In and Advances to Real Estate Joint Ventures - The Company's Share of Net Income/(Loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Prudential Investment Program [Member]
Income of joint ventures, net	[1]	$ 2,400	$ 2,600
KIR [Member]
Income of joint ventures, net		13,400	8,700
CPP [Member]
Income of joint ventures, net		3,100	2,100
Other Institutional Joint Ventures [Member]
Income of joint ventures, net		1,500	0
Other Joint Venture Programs [Member]
Income of joint ventures, net		3,200	4,400
Joint Ventures [Member]
Income of joint ventures, net		$ 23,570	$ 17,752

[1] During the year ended December 31, 2019, the Prudential Investment Program recognized an impairment charge on a property of $29.9 million, of which the Company’s share was $3.7 million.