Note 5 - Investments In and Advances to Real Estate Joint Ventures - Joint Venture Investments Accounted for Under the Equity Method, Debt Details (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2019	Dec. 31, 2018
Mortgage and notes payable		$ 1,671.3	$ 1,782.6
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 562.9	$ 572.6
Weighted average interest rate		4.02%	4.29%
Weighted average remaining term (Month)	[1]	51 months 24 days	49 months
KIR [Member]
Mortgage and notes payable		$ 572.0	$ 651.4
Weighted average interest rate		4.48%	4.43%
Weighted average remaining term (Month)	[1]	34 months	40 months 12 days
CPP [Member]
Mortgage and notes payable		$ 84.7	$ 84.4
Weighted average interest rate		3.95%	3.85%
Weighted average remaining term (Month)	[1]	48 months 3 days	54 months
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 451.7	$ 474.2
Weighted average interest rate		4.19%	4.26%
Weighted average remaining term (Month)	[1]	77 months 12 days	78 months 18 days

[1] * Includes extension options