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, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Gains (losses) on derivative and other hedging instruments	$ 335,368	$ (8,772)	$ 444,076	$ (136,717)
Short [Member] \| US Treasury Securities [Member]
Gains (losses) on derivative and other hedging instruments	(1,105)	0	(2,750)	0
Interest Rate Futures Contracts [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	40,836	(3,159)	49,495	(26,789)
Interest Rate Swap [Member]
Gains (losses) on derivative and other hedging instruments	266,648	(2,298)	371,003	(102,549)
Payer Swaptions [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	14,866	0	13,376	0
Payer Swaptions [Member] \| Long [Member]
Gains (losses) on derivative and other hedging instruments	(5,608)	0	(4,676)	0
TBA Contracts [Member] \| Short [Member]
Gains (losses) on derivative and other hedging instruments	20,911	(4,272)	17,877	(8,908)
TBA Contracts [Member] \| Long [Member]
Gains (losses) on derivative and other hedging instruments	$ (1,180)	$ 957	$ (249)	$ 1,529