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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Prudential Investment Program [Member]
Income of joint ventures, net	$ 2,600	$ 1,800	$ 5,300	$ 4,400
KIR [Member]
Income of joint ventures, net	9,100	5,000	17,800	14,700
CPP [Member]
Income of joint ventures, net	2,000	1,700	4,100	2,700
Other Joint Venture Programs [Member]
Income of joint ventures, net	2,600	1,700	6,900	2,000
Joint Ventures [Member]
Income of joint ventures, net	$ 16,318	$ 10,158	$ 34,070	$ 23,806