Note 5 - Investments Investments Trading Securities (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Marketable Securities, Unrealized Gain (Loss)	$ 18,800,000	$ 65,700,000
Trading Securities	1,574,795,000	1,633,584,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	135,801,000	134,530,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	334,052,000	343,926,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	699,621,000	708,361,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	86,294,000	89,810,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	178,563,000	188,615,000
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	55,386,000	77,755,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	13,731,000	18,331,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 71,347,000	$ 72,256,000