Note 7 - 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, 2020	Dec. 31, 2019	Dec. 31, 2018
Prudential Investment Program [Member]
Income of joint ventures, net	[1]	$ 9,000	$ 10,400	$ 15,200
KIR [Member]
Income of joint ventures, net		30,500	50,300	38,700
CPP [Member]
Income of joint ventures, net		5,600	5,800	5,100
Other Joint Venture Programs [Member]
Income of joint ventures, net	[2]	2,300	5,700	12,600
Joint Ventures [Member]
Income of joint ventures, net		$ 47,353	$ 72,162	$ 71,617

[1] During the year ended December 31, 2019, the Prudential Investment Program recognized an impairment charge on a property of $29.9 million, of which the Company's share was $3.7 million.

[2] During the year ended December 31, 2018, a joint venture investment distributed cash proceeds resulting from the refinancing of an existing loan of which the Company's share was $3.6 million. This distribution was in excess of the Company’s carrying basis in this joint venture investment and to that extent was recognized as income. In addition, during the year ended December 31, 2018, a joint venture recognized an impairment charge related to the pending foreclosure of a property, of which the Company’s share was $5.2 million.