Note 4 - Investments and Advances in Real Estate Joint Ventures - Summary of Properties and Land Parcels Disposed of (Details) $ in Millions		9 Months Ended
		Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Kim Pru and Kim Pru II [Member]
Number of properties		1	5
Number of Land Parcels			1
Aggregate Sales Price		$ 16.5	$ 84.0
Net gain, before income taxes		$ 0.4	$ (0.8)
KIR [Member]
Number of properties		1	4
Number of Land Parcels
Aggregate Sales Price		$ 23.6	$ 72.6
Net gain, before income taxes		$ 4.6	$ 9.0
CPP [Member]
Number of properties	[1]	2
Number of Land Parcels	[1]
Aggregate Sales Price	[1]	$ 299.2
Net gain, before income taxes	[1]
Other Joint Venture Programs [Member]
Number of properties		2	10	[2]
Number of Land Parcels			9	[2]
Aggregate Sales Price		$ 21.6	$ 139.9	[2]
Net gain, before income taxes		$ 2.4	$ (1.1)	[2]
Other Institutional Programs [Member]
Number of properties	[3]	6
Number of Land Parcels	[3]
Aggregate Sales Price	[3]	$ 189.8
Net gain, before income taxes	[3]	$ 0.4
Canadian Properties [Member]
Number of properties		34	4
Number of Land Parcels			1
Aggregate Sales Price		$ 894.7	$ 204.2
Net gain, before income taxes		$ 135.5	$ 54.6
Number of properties		46	23
Number of Land Parcels			11
Aggregate Sales Price		$ 1,445.4	$ 500.7
Net gain, before income taxes		$ 143.3	$ 61.7

[1] In April 2016, the Company acquired its partner's interest in an operating property and a development project for a gross purchase price of $299.2 million, including the assumption of $100.0 million in mortgage debt, which encumbered the operating property.

[2] The Company acquired the remaining interest in two of these properties during the nine months ended September 30, 2015.

[3] The Company acquired the remaining interest in five of these properties during the nine months ended September 30, 2016 (see Footnote 2).