Note 4 - Investments in and Advances to Real Estate Joint Ventures - Joint Venture Investments Accounted for Under the Equity Method, Debt Details (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Mortgage and notes payable		$ 1,726.5	$ 2,063.0
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 626.9	$ 647.4
Weighted average interest rate		3.35%	3.07%
Weighted average remaining term (Month)	[1]	5 years 87 days	5 years 225 days
KIR [Member]
Mortgage and notes payable		$ 725.7	$ 746.5
Weighted average interest rate		4.54%	4.64%
Weighted average remaining term (Month)	[1]	4 years 51 days	4 years 207 days
CPP [Member]
Mortgage and notes payable		$ 84.9	$ 84.8
Weighted average interest rate		2.78%	2.17%
Weighted average remaining term (Month)	[1]	210 days	1 year 120 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 289.0	$ 584.3
Weighted average interest rate		4.37%	5.40%
Weighted average remaining term (Month)	[1]	2 years 174 days	1 year 342 days

[1] Includes extension options