Note 2 - Mortgage-backed Securities and U.S. Treasury Securities, at Fair Value - Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Sales and maturities	$ 1,380,091	$ 454,272	$ 797,633
Carrying value of RMBS sold	(1,386,412)	(458,874)	(820,275)
Realized losses on mortgage-backed securities	(6,321)	(4,602)	(22,642)
Gross gain on sales of RMBS	2,975	510	2,705
Gross loss on sales of RMBS	$ (9,296)	$ (5,112)	$ (25,347)