Note 7 - Investment in and Advances to Real Estate Joint Ventures - Joint Venture Investments Accounted for Under the Equity Method, Debt Details (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Mortgage and notes payable		$ 1,782.6	$ 1,700.2
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 572.6	$ 625.7
Weighted average interest rate		4.29%	3.59%
Weighted average remaining term (Month)	[1]	4 years 30 days	4 years 354 days
KIR [Member]
Mortgage and notes payable		$ 651.4	$ 702.0
Weighted average interest rate		4.43%	4.60%
Weighted average remaining term (Month)	[1]	3 years 132 days	3 years 345 days
CPP [Member]
Mortgage and notes payable		$ 84.4	$ 84.9
Weighted average interest rate		3.85%	2.91%
Weighted average remaining term (Month)	[1]	4 years 180 days	120 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 474.2	$ 287.6
Weighted average interest rate		4.26%	4.41%
Weighted average remaining term (Month)	[1]	6 years 198 days	2 years 96 days

[1] Average remaining term includes extensions