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, 2019	Dec. 31, 2018	Dec. 31, 2017
Prudential Investment Program [Member]
Income of joint ventures, net	[1]	$ 10,400	$ 15,200	$ 13,000
KIR [Member]
Income of joint ventures, net		50,300	38,700	36,700
CPP [Member]
Income of joint ventures, net		5,800	5,100	7,200
Other Joint Venture Programs [Member]
Income of joint ventures, net	[2],[3],[4],[5]	5,700	12,600	3,900
Joint Ventures [Member]
Income of joint ventures, net		$ 72,162	$ 71,617	$ 60,763

[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, 2017, a joint venture recognized an impairment charge related to the pending sale of a property, of which the Company's share was $3.4 million.

[3] During the year ended December 31, 2017, the Company recognized a cumulative foreign currency translation loss of $4.8 million due to the substantial liquidation of the Company's investments in Canada during 2017.

[4] 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.

[5] 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.