Note 6 - Other Real Estate Investments (Details Textual) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Equity Method Investments	$ 584,983		$ 570,922
Preferred Equity Investments [Member]
Income (Loss) from Equity Method Investments, Total	19,500	$ 19,500
Equity Method Investment, Realized Gain (Loss) on Disposal, Total	$ 9,800	$ 10,000
Preferred Equity Investments [Member]
Number of Real Estate Properties	247
Preferred Equity Investments [Member] | Maximum Exposure [Member]
Equity Method Investments	$ 173,500
Preferred Equity Investments [Member] | Leased Properties [Member]
Number of Real Estate Properties	236