Note 9 - Financing Arrangements, Portfolio Investments (Details) - Assets Pledged as Collateral (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	$ 627,881	$ 791,125
Fair Value of Collateral Pledged	683,914	853,223
Amortized Cost Of Collateral Pledged	710,906	887,444
Agency ARMs [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	152,735	197,974
Fair Value of Collateral Pledged	163,112	208,703
Amortized Cost Of Collateral Pledged	165,517	214,039
Agency Fixed Rate [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	393,141	489,953
Fair Value of Collateral Pledged	419,560	516,010
Amortized Cost Of Collateral Pledged	433,849	541,580
Agency IOs [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements	82,005	94,698
Fair Value of Collateral Pledged	101,242	113,721
Amortized Cost Of Collateral Pledged	111,540	122,878
Collateralized Loan Obligation [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Outstanding Repurchase Agreements		8,500
Fair Value of Collateral Pledged		14,789
Amortized Cost Of Collateral Pledged		$ 8,947