Note 16 - Preferred Stock, Common Stock and Convertible Unit Transactions - Preferred Stock Redeemed (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
		Sep. 06, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Redemption Charges				$ 7,014
Series I Preferred Stock [Member]
Depositary Shares Redeemed (in shares)		9,000,000		9,000,000	[1],[2]
Offering/ Redemption Price (in dollars per share)	[2]			$ 25
Redemption Amount	[2]			$ 225,000
Redemption Charges	[1],[2]			$ 7,000

[1] Redemption charges resulting from the difference between the redemption amount and the carrying amount of the respective preferred stock class on the Company' Consolidated Balance Sheets are accounted for in accordance with the FASB's guidance on Distinguishing Liabilities from Equity. These charges were subtracted from net income attributable to the Company to arrive at net income available to the Company's common shareholders and used in the calculation of earnings per share.

[2] The Company partially redeemed 9,000,000 depositary shares of its issued and outstanding Class I Preferred Stock, representing 56.25% of the issued and outstanding Class I Preferred Stock.