Note 8 - Derivatives Instruments and Hedging Activities (Details) - Fair Value of Derivative Instruments Not Designated as Hedging Instruments (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
TBA Securities [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Assets	$ 214,711	[1]	$ 190,742	[1]
US Treasury Futures [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Assets			3,257
Derivatives Not Designated As Hedging Instruments - Liabilities	49
Swaption [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Assets	245		1,305
Options on U.S. Treasury Futures [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Assets			7
Interest Rate Swap [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Assets	476		238
Eurodollar Future [Member]
Derivative [Line Items]
Derivatives Not Designated As Hedging Instruments - Liabilities	$ 370		$ 1,432

[1] Open TBA purchases and sales involving the same counterparty, same underlying deliverable and the same settlement date are reflected in our accompanying condensed consolidated financial statements on a net basis. There was no netting of TBA sales against TBA purchases at September 30, 2014 and December 31, 2013.