Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments Gain (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Gains on derivative instruments	$ 133,554	$ 45,237	$ 452,476
Treasury Note Future [Member] | Short [Member]
Gains on derivative instruments	26,638	32,650	206,907
Interest Rate Swap [Member]
Gains on derivative instruments	101,151	19,657	167,641
Payer Swaptions [Member] | Short [Member]
Gains on derivative instruments	(72)	(8,734)	152,365
Payer Swaptions [Member] | Long [Member]
Gains on derivative instruments	0	4,113	(81,050)
Interest Rate Cap [Member]
Gains on derivative instruments	0	(219)	919
Dual Digital Option [Member]
Gains on derivative instruments	(500)	0	0
Interest Rate Floor [Member] | Short [Member]
Gains on derivative instruments	0	1,785	0
Interest Rate Floor [Member] | Long [Member]
Gains on derivative instruments	0	(525)	0
TBA Contracts [Member] | Short [Member]
Gains on derivative instruments	6,567	1,370	4,494
TBA Contracts [Member] | Long [Member]
Gains on derivative instruments	$ (230)	$ (4,860)	$ 1,200