Note 4 - Investments and Advances in 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, 2016	Dec. 31, 2015
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 791.5	$ 777.1
Weighted average interest rate		3.36%	5.54%
Weighted average remaining term	[1]	4 years 252 days	1 year 18 days
KIR [Member]
Mortgage and notes payable		$ 776.2	$ 811.6
Weighted average interest rate		4.69%	4.64%
Weighted average remaining term	[1]	4 years 222 days	5 years 69 days
CPP [Member]
Mortgage and notes payable		$ 84.5	$ 109.9
Weighted average interest rate		2.08%	5.25%
Weighted average remaining term	[1]	1 year 210 days	105 days
Other Institutional Programs [Member]
Mortgage and notes payable		$ 94.6	$ 218.5
Weighted average interest rate		4.07%	4.92%
Weighted average remaining term	[1]	2 years 9 days	1 year 255 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 535.3	$ 540.7
Weighted average interest rate		5.56%	5.61%
Weighted average remaining term	[1]	2 years 120 days	3 years 3 days
Canadian Properties [Member]
Mortgage and notes payable		$ 7.8	$ 341.3
Weighted average interest rate		4.70%	4.64%
Weighted average remaining term		1 year 6 days	4 years 252 days
Mortgage and notes payable		$ 2,289.9	$ 2,799.1

[1] Average Remaining Term includes extension options.