Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
(Losses) gains on derivative and other hedging instruments	$ (74,659)	$ 87,899
Treasury Note Future [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	(14,942)	19,090
Interest Rate Swap [Member]
(Losses) gains on derivative and other hedging instruments	(62,843)	59,098
Payer Swaptions [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	0	(58)
Dual Digital Option [Member]
(Losses) gains on derivative and other hedging instruments	0	(239)
TBA Contracts [Member] | Short [Member]
(Losses) gains on derivative and other hedging instruments	3,026	9,903
TBA Contracts [Member] | Long [Member]
(Losses) gains on derivative and other hedging instruments	$ 100	$ 105