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		6 Months Ended	12 Months Ended
		Jun. 30, 2016	Dec. 31, 2015
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 744.6	$ 777.1
Weighted average interest rate		5.24%	5.54%
Weighted average remaining term	[1]	1 year 117 days	1 year 18 days
KIR [Member]
Mortgage and notes payable		$ 780.1	$ 811.6
Weighted average interest rate		4.69%	4.64%
Weighted average remaining term	[1]	4 years 315 days	5 years 69 days
CPP [Member]
Mortgage and notes payable		$ 84.4	$ 109.9
Weighted average interest rate		2.02%	5.25%
Weighted average remaining term	[1]	1 year 300 days	105 days
Other Institutional Programs [Member]
Mortgage and notes payable		$ 215.6	$ 218.5
Weighted average interest rate		4.92%	4.92%
Weighted average remaining term	[1]	1 year 108 days	1 year 255 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 536.4	$ 540.7
Weighted average interest rate		5.55%	5.61%
Weighted average remaining term	[1]	2 years 210 days	3 years 3 days
Canadian Properties [Member]
Mortgage and notes payable		$ 30.7	$ 341.3
Weighted average interest rate		4.99%	4.64%
Weighted average remaining term		3 years 264 days	4 years 252 days
Mortgage and notes payable		$ 2,391.8	$ 2,799.1

[1] Average Remaining Term includes extension options.