Note 6 - Other Real Estate Investments (Details Textual) - Preferred Equity Investments [Member] $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Number of Real Estate Properties	243
Income (Loss) from Equity Method Investments, Total	$ 22.6	$ 24.4
Equity Method Investment, Realized Gain (Loss) on Disposal, Total	9.8	$ 10.5
Leased Properties [Member]
Equity Method Investments	$ 176.0
Number of Real Estate Properties	232