Note 5 - Investments Investments Trading Securities (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 1,123,038	$ 1,279,137
Marketable Securities, Unrealized Gain (Loss)	58,400	(25,200)
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	33,874	129,913
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	299,042	303,946
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	596,018	580,993
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	66,239	72,192
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	107,608	137,678
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	6,826	16,131
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	13,431	13,268
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 0	$ 25,016