Note 5 - Derivative and Other Hedging Instruments - Schedule of Derivative Instruments Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Gains (losses) on derivative and other hedging instruments	$ 87,899	$ (41,156)
Treasury Note Future [Member] | Short [Member]
Gains (losses) on derivative and other hedging instruments	19,090	(4,038)
Interest Rate Swap [Member]
Gains (losses) on derivative and other hedging instruments	59,098	(26,144)
Payer Swaptions [Member] | Short [Member]
Gains (losses) on derivative and other hedging instruments	0	6,585
Payer Swaptions [Member] | Long [Member]
Gains (losses) on derivative and other hedging instruments	(58)	(12,109)
Interest Rate Cap [Member]
Gains (losses) on derivative and other hedging instruments	0	(645)
Dual Digital Option [Member]
Gains (losses) on derivative and other hedging instruments	(239)	0
Interest Rate Floor [Member] | Short [Member]
Gains (losses) on derivative and other hedging instruments	0	1,185
TBA Contracts [Member] | Short [Member]
Gains (losses) on derivative and other hedging instruments	9,903	(5,990)
TBA Contracts [Member] | Long [Member]
Gains (losses) on derivative and other hedging instruments	$ 105	$ 0