Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments in Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Restricted Cash and Cash Equivalents, Current	$ 28,396	$ 31,568
Other liabilites	(1,031)	(25,119)
Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative assets, at fair value	6,420	40,172
Derivative liabilities, at fair value	12,694	7,161
Total margin balances on derivative contracts	28,396	5,206
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Swap [Member]
Derivative assets, at fair value	6,348	4,983
Derivative liabilities, at fair value	0	0
Other liabilites	0	(12,489)
Not Designated as Hedging Instrument, Economic Hedge [Member] | Payer Swaptions [Member] | Long [Member]
Derivative assets, at fair value	72	33,398
Not Designated as Hedging Instrument, Economic Hedge [Member] | Payer Swaptions [Member] | Short [Member]
Derivative liabilities, at fair value	0	5,982
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Cap [Member]
Derivative assets, at fair value	0	1,119
Not Designated as Hedging Instrument, Economic Hedge [Member] | TBA Contracts [Member]
Derivative assets, at fair value	0	672
Derivative liabilities, at fair value	12,694	1,179
Restricted Cash and Cash Equivalents, Current	23,720	1,734
Other liabilites	0	(532)
Not Designated as Hedging Instrument, Economic Hedge [Member] | Eurodollar Future Margin [Member]
Restricted Cash and Cash Equivalents, Current	4,096	16,493
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Swaption [Member]
Restricted Cash and Cash Equivalents, Current	$ 580	$ 0