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, 2020	Mar. 31, 2019
Prudential Investment Program [Member]
Income of joint ventures, net	$ 2,600	$ 2,900
KIR [Member]
Income of joint ventures, net	9,800	14,500
CPP [Member]
Income of joint ventures, net	1,000	1,400
Other Joint Venture Programs [Member]
Income of joint ventures, net	200	0
Joint Ventures [Member]
Income of joint ventures, net	$ 13,648	$ 18,754