Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
(Losses) gains on derivative and other hedging instruments	$ (140,825)	$ 142,042	$ (26,858)	$ 194,253
Treasury Note Future [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	(14,668)	42,640	16,100	66,642
Interest Rate Swap [Member]
(Losses) gains on derivative and other hedging instruments	(110,085)	78,317	(39,469)	101,257
Payer Swaptions [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	0	(718)	0	4,113
Payer Swaptions [Member] | Long [Member]
(Losses) gains on derivative and other hedging instruments	0	1,613	(72)	(7,389)
Interest Rate Cap [Member]
(Losses) gains on derivative and other hedging instruments	0	493	0	(415)
Dual Digital Option [Member]
(Losses) gains on derivative and other hedging instruments	(105)	0	(500)	0
Interest Rate Floor [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	0	73	0	(1,143)
Interest Rate Floor [Member] | Long [Member]
(Losses) gains on derivative and other hedging instruments	0	137	0	2,666
TBA Contracts [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	(16,315)	21,511	(3,370)	31,120
TBA Contracts [Member] | Long [Member]
(Losses) gains on derivative and other hedging instruments	$ 348	$ (2,024)	$ 453	$ (2,598)