Note 6 - Investments Investments Trading Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 1,633,584,000	$ 2,238,741,000
Trading Securities, Change in Unrealized Holding Gain (Loss)	92,226,000	(117,198,000)	(36,435,000)
Investments	3,629,299,000	3,361,678,000
Securities (Assets)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities, Change in Unrealized Holding Gain (Loss)	65,700,000	88,400,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	134,530,000	240,860,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	343,926,000	356,715,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	708,361,000	868,403,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	89,810,000	338,776,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	188,615,000	209,191,000
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	77,755,000	121,399,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	18,331,000	28,303,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	72,256,000	75,094,000
Portugal, Ireland, Italy, Greece, Spain and Hungary Government Securities [Member] | Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	0	0
Non European Countries Outside U.S. Under Economic Stress [Member] | Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investments	$ 0	$ 0