Note 3 - Joint Venture Investments Accounted for under the Equity Method - Debt Details (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 729.4	$ 777.1
Weighted average interest rate		5.55%	5.54%
Weighted average remaining term	[1]	9 years 255 days	12 years 219 days
KIR [Member]
Mortgage and notes payable		$ 808.6	$ 811.6
Weighted average interest rate		4.61%	4.64%
Weighted average remaining term	[1]	60 years 255 days	62 years 109 days
CPP [Member]
Mortgage and notes payable		$ 149.1	$ 109.9
Weighted average interest rate		1.97%	5.25%
Weighted average remaining term	[1]	22 years 146 days	3 years 182 days
Other Institutional Programs [Member]
Mortgage and notes payable		$ 215.4	$ 218.5
Weighted average interest rate		4.91%	4.92%
Weighted average remaining term	[1]	17 years 292 days	20 years 182 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 537.3	$ 540.7
Weighted average interest rate		5.55%	5.61%
Weighted average remaining term	[1]	34 years	36 years 36 days
Canadian Properties [Member]
Mortgage and notes payable		$ 241.2	$ 341.3
Weighted average interest rate		4.33%	4.64%
Weighted average remaining term		52 years 219 days	56 years 146 days
Mortgage and notes payable		$ 2,681.0	$ 2,799.1

[1] Average Remaining Term includes extension options.