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, 2021	Mar. 31, 2020
Prudential Investment Program [Member]
Income of joint ventures, net	$ 2,600	$ 2,600
KIR [Member]
Income of joint ventures, net	8,700	9,800
CPP [Member]
Income of joint ventures, net	2,100	1,000
Other Joint Venture Programs [Member]
Income of joint ventures, net	4,400	200
Joint Ventures [Member]
Income of joint ventures, net	$ 17,752	$ 13,648