Note 5 - Derivative and Other Hedging Instruments - Schedule of Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Payer Swaptions Less than or Equal to One Year [Member] | Long [Member]
Cost	$ 1,619	$ 36,685
Net Estimated Fair Value	$ 1,418	$ 21,253
Weighted average months to expiration (Month)	8 months	9 months 18 days
Notional Amount	$ 800,000	$ 1,250,000
Average fixed pay rate	5.40%	4.09%
Weighted average term (Year)	1 year	10 years
Notional Amount	$ (800,000)	$ (1,250,000)
Payer Swaptions [Member] | Long [Member]
Cost	1,619	47,706
Net Estimated Fair Value	$ 1,418	$ 33,398
Weighted average months to expiration (Month)	8 months	29 months 24 days
Notional Amount	$ 800,000	$ 1,370,000
Average fixed pay rate	5.40%	3.91%
Weighted average term (Year)	1 year	10 years
Notional Amount	$ (800,000)	$ (1,370,000)
Payer Swaptions [Member] | Short [Member]
Cost		(17,800)
Net Estimated Fair Value		$ (5,982)
Weighted average months to expiration (Month)		3 months 18 days
Notional Amount		$ 917,000
Average fixed pay rate		4.09%
Weighted average term (Year)		10 years
Notional Amount		$ (917,000)
Payer Swaptions, Greater Than Ten Years [Member] | Long [Member]
Cost		11,021
Net Estimated Fair Value		$ 12,145
Weighted average months to expiration (Month)		239 months 15 days
Notional Amount		$ 120,000
Average fixed pay rate		2.05%
Weighted average term (Year)		10 years
Notional Amount		$ (120,000)