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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Prudential Investment Program [Member]
Income of joint ventures, net	$ 3,400	$ 2,600	$ 15,400	$ 7,400
KIR [Member]
Income of joint ventures, net	8,200	17,500	26,000	62,900
CPP [Member]
Income of joint ventures, net	1,500	2,500	6,900	8,200
Other Institutional Joint Ventures [Member]
Income of joint ventures, net	700	800	2,200	6,300
Other Joint Venture Programs [Member]
Income of joint ventures, net	2,500	3,000	7,100	9,300
Joint Ventures [Member]
Income of joint ventures, net	$ 16,257	$ 26,360	$ 57,589	$ 94,060