Note 8 - Investment and Advances in Real Estate Joint Ventures - Joint Venture Investments Accounted for Under the Equity Method, Debt Details (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Mortgage and notes payable		$ 2,063.0	$ 2,799.1
Kim Pru and Kim Pru II [Member]
Mortgage and notes payable		$ 647.4	$ 777.1
Weighted average interest rate		3.07%	5.54%
Weighted average remaining term (Month)	[1]	5 years 225 days	1 year 18 days
KIR [Member]
Mortgage and notes payable		$ 746.5	$ 811.6
Weighted average interest rate		4.64%	4.64%
Weighted average remaining term (Month)	[1]	4 years 207 days	5 years 69 days
CPP [Member]
Mortgage and notes payable		$ 84.8	$ 109.9
Weighted average interest rate		2.17%	5.25%
Weighted average remaining term (Month)	[1]	1 year 120 days	105 days
Other Institutional Programs [Member]
Mortgage and notes payable		$ 94.7	$ 218.5
Weighted average interest rate		4.09%	4.92%
Weighted average remaining term (Month)	[1]	1 year 210 days	1 year 255 days
Other Joint Venture Programs [Member]
Mortgage and notes payable		$ 482.1	$ 540.7
Weighted average interest rate		5.67%	5.61%
Weighted average remaining term (Month)	[1]	2 years 15 days	3 years 3 days
Canadian Properties [Member]
Mortgage and notes payable		$ 7.5	$ 341.3
Weighted average interest rate		4.70%	4.64%
Weighted average remaining term (Month)	[1]	273 days	4 years 252 days

[1] Average remaining term includes extensions