Note 5 - Investments Investments Trading Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 969,657	$ 1,279,137
Marketable Securities, Unrealized Gain (Loss)	53,700	(25,200)
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	33,781	129,913
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	273,564	303,946
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	504,335	580,993
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	41,773	72,192
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	91,981	137,678
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	10,747	16,131
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	13,476	13,268
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 0	$ 25,016