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, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Gains (losses) on derivative and other hedging instruments	$ 62,400	$ (53,286)	$ 108,708	$ (127,945)
Short [Member] \| US Treasury Securities [Member]
Gains (losses) on derivative and other hedging instruments	(1,042)	0	(1,645)	0
Interest Rate Futures Contracts [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	4,222	(8,688)	8,659	(23,630)
Interest Rate Swap [Member]
Gains (losses) on derivative and other hedging instruments	63,353	(37,408)	104,355	(100,251)
Payer Swaptions [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	(1,490)	0	(1,490)	0
Payer Swaptions [Member] \| Long [Member]
Gains (losses) on derivative and other hedging instruments	932	0	932	0
TBA Contracts [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	(3,228)	(7,662)	(3,033)	(4,636)
TBA Contracts [Member] \| Long [Member]
Gains (losses) on derivative and other hedging instruments	$ (347)	$ 472	$ 930	$ 572