Note 5 - Investments Investments Trading Securities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Schedule of Trading Securities and Other Trading Assets [Line Items]
Unrealized Gain (Loss) on Trading Securities Held	$ 3,500	$ 16,800
Trading Securities	811,313	879,862
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	33,006	33,042
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	235,864	259,573
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	420,633	453,617
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	35,911	38,214
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	70,980	78,984
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	6,733	8,219
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 8,186	$ 8,213