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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Prudential Investment Program [Member]
Income of joint ventures, net	$ 1,800	$ 2,800	$ 4,400	$ 5,700
KIR [Member]
Income of joint ventures, net	5,000	17,200	14,700	31,800
CPP [Member]
Income of joint ventures, net	1,700	1,600	2,700	3,000
Other Joint Venture Programs [Member]
Income of joint ventures, net	1,700	900	2,000	800
Joint Ventures [Member]
Income of joint ventures, net	$ 10,158	$ 22,533	$ 23,806	$ 41,287