Note 5 - Dispositions of Real Estate and Assets Held-for-sale - Disposition Activity (Details) - Disposition Activity Relating to Consolidated Operating Properties and Parcels [Member] $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)	[1]	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Aggregate sales price/gross fair value	$ 344.7		$ 1,164.3	$ 352.2
Gain on sale of operating properties/change in control of interests	$ 79.2		$ 229.8	$ 93.5
Number of operating properties sold/deconsolidated	20		54	25
Number of out-parcels sold	9		7	9

[1] Includes the land parcel sale at Dania Pointe, noted above in Footnote 4 of the Notes to Consolidated Financial Statements.