Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Gains on derivative and other hedging instruments	$ 26,068	$ 93,367	$ 113,967	$ 52,211
Treasury Note Future [Member] | Short [Member]
Gains on derivative and other hedging instruments	11,678	28,040	30,768	24,002
Interest Rate Swap [Member]
Gains on derivative and other hedging instruments	11,518	49,084	70,616	22,940
Payer Swaptions [Member] | Short [Member]
Gains on derivative and other hedging instruments	0	(1,754)	0	4,831
Payer Swaptions [Member] | Long [Member]
Gains on derivative and other hedging instruments	(14)	3,107	(72)	(9,002)
Interest Rate Cap [Member]
Gains on derivative and other hedging instruments	0	(263)	0	(908)
Dual Digital Option [Member]
Gains on derivative and other hedging instruments	(156)	0	(395)	0
Interest Rate Floor [Member] | Short [Member]
Gains on derivative and other hedging instruments	0	(1,216)	0	(1,216)
Interest Rate Floor [Member] | Long [Member]
Gains on derivative and other hedging instruments	0	1,344	0	2,529
TBA Contracts [Member] | Short [Member]
Gains on derivative and other hedging instruments	3,042	15,599	12,945	9,609
TBA Contracts [Member] | Long [Member]
Gains on derivative and other hedging instruments	$ 0	$ (574)	$ 105	$ (574)