Note 6 - Investments in and Advances to Real Estate Joint Ventures - The Company's Share of Net Income/(Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income of joint ventures, net		$ 10,709	$ 17,403	$ 23,172
Prudential Investment Program [Member]
Income of joint ventures, net	[1]	16,400	9,600	17,500
KIR [Member]
Income of joint ventures, net		34,700	70,300	36,900
CPP [Member]
Income of joint ventures, net		8,700	10,600	9,200
Other Institutional Joint Ventures [Member]
Income of joint ventures, net		2,600	7,000	1,700
Other Joint Venture Programs [Member]
Income of joint ventures, net		9,900	12,000	19,500
Joint Ventures [Member]
Income of joint ventures, net		$ 72,278	$ 109,481	$ 84,778

[1] During 2022, the Prudential Investment Program recognized an impairment charge on a property of $15.1 million, of which the Company’s share was $2.3 million.