Note 5 - Other Real Estate Investments (Details Textual) - Preferred Equity Investments [Member] $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Equity Method Investments	$ 101.2
Number of Real Estate Properties	131
Income (Loss) from Equity Method Investments, Total	$ 26.8	$ 22.6
Equity Method Investment, Realized Gain (Loss) on Disposal, Total	$ 15.9	$ 8.6
Leased Properties [Member]
Number of Real Estate Properties	121

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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