Note 17 - Preferred Stock, Common Stock and Convertible Unit Transactions - Preferred Stock Issued (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Proceeds, After Expenses	$ 286,421	$ 493	$ 14,047
Series I Preferred Stock [Member]
Depositary Shares Issued (in shares)		16,000,000
Net Proceeds, After Expenses		$ 387,200
Offering/ Redemption Price (in dollars per share)		$ 25
Series J Preferred Stock [Member]
Depositary Shares Issued (in shares)		9,000,000
Net Proceeds, After Expenses		$ 217,800
Offering/ Redemption Price (in dollars per share)		$ 25
Series K Preferred Stock [Member]
Depositary Shares Issued (in shares)		7,000,000
Net Proceeds, After Expenses		$ 169,100
Offering/ Redemption Price (in dollars per share)		$ 25