Note 6 - Other Real Estate Investments (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Equity Method Investments	$ 566,928		$ 570,922
Preferred Equity Investments [Member]
Number of Real Estate Properties	285
Income (Loss) from Equity Method Investments, Total	$ 6,500	$ 10,000
Equity Method Investment, Realized Gain (Loss) on Disposal, Total	$ 1,000	$ 4,700
Preferred Equity Investments [Member] | Leased Properties [Member]
Number of Real Estate Properties	273
Preferred Equity Investments [Member] | Maximum Exposure [Member]
Equity Method Investments	$ 186,600