Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Unrealized Gains (Losses)	$ (1,020)		$ (1,498)		$ (4,047)		$ 3,014
TBA [Member]
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Realized Gains (Losses)	2,652		(5,420)		10,007		(15,834)
Unrealized Gains (Losses)	(2,348)		6,377		198		4,962
Eurodollar Future [Member]
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Realized Gains (Losses)	(441)	[1]	(1,096)	[1]	(1,879)	[1]	(2,886)	[1]
Unrealized Gains (Losses)	853	[1]	(32)	[1]	1,061	[1]	1,906	[1]
Swaption [Member]
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Unrealized Gains (Losses)	73		(312)		(769)		1,077
US Treasury Futures and Interest Rate Swap Futures and Options [Member]
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Realized Gains (Losses)	(1,629)		9,793		(4,155)		10,520
Unrealized Gains (Losses)	2,241		(11,122)		(2,999)		(4,282)
Not Designated as Hedging Instrument [Member]
Note 8 - Derivatives Instruments and Hedging Activities (Details) - Components of Realized and Unrealized Gains and Losses [Line Items]
Realized Gains (Losses)	582		3,277		3,973		(8,200)
Unrealized Gains (Losses)	$ 819		$ (5,089)		$ (2,509)		$ 3,663

[1] At September 30, 2014, the Eurodollar futures consist of 2,778 contracts with expiration dates ranging between December 2014 and September 2017.