Note 7 - Investments In and Advances to Real Estate Joint Ventures - The Company's Share of Net Income/(Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Prudential Investment Program [Member]
Income of joint ventures, net	[1]	$ 17,500	$ 9,000	$ 10,400
KIR [Member]
Income of joint ventures, net		36,900	30,500	50,300
CPP [Member]
Income of joint ventures, net		9,200	5,600	5,800
Other Institutional Joint Ventures [Member]
Income of joint ventures, net		1,700	0	0
Other Joint Venture Programs [Member]
Income of joint ventures, net		19,500	2,300	5,700
Joint Ventures [Member]
Income of joint ventures, net		$ 84,778	$ 47,353	$ 72,162

[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.