Note 3 - Operating Property Activities - Disposition Activity (Details) - Disposition Activity Relating to Consolidated Operating Properties and Parcels [Member] $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Aggregate sales price/gross fair value	$ 973.5	$ 230.2
Gain on sale of operating properties/change in control of interests	180.5	62.1
Impairment charges	$ 16.3	$ 13.0
Number of operating properties sold/deconsolidated	45	15
Number of out-parcels sold	4	8

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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