Note 5 - Investments Investments Trading Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Marketable Securities, Unrealized Gain (Loss)	$ (12,700)	$ 65,700
Trading Securities	1,414,757	1,633,584
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	131,956	134,530
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	313,884	343,926
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	632,681	708,361
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	76,536	89,810
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	156,697	188,615
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	25,559	77,755
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	13,449	18,331
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 63,995	$ 72,256