Note 4 - Derivative and Other Hedging Instruments - Schedule of Fair Value of Derivative Instruments (Details) - Payer Swaptions [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Long [Member]
Cost	$ 46,800	$ 47,706
Net Estimated Fair Value	$ 14,849	$ 33,398
Weighted average months to expiration (Month)	13 months 9 days	29 months 24 days
Notional amount	$ (2,250,000)	$ (1,370,000)
Average fixed pay rate	3.82%	3.91%
Weighted average term (Year)	6 years 4 months 24 days	10 years
Notional amount	$ 2,250,000	$ 1,370,000
Less than or Equal to One Year [Member] | Long [Member]
Cost	36,685	36,685
Net Estimated Fair Value	$ 6,548	$ 21,253
Weighted average months to expiration (Month)	6 months 18 days	9 months 18 days
Notional amount	$ (1,250,000)	$ (1,250,000)
Average fixed pay rate	4.09%	4.09%
Weighted average term (Year)	10 years	10 years
Notional amount	$ 1,250,000	$ 1,250,000
Less than or Equal to One Year [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
More Than One Year [Member] | Long [Member]
Cost	10,115
Net Estimated Fair Value	$ 8,301
Weighted average months to expiration (Month)	21 months 21 days
Notional amount	$ (1,000,000)
Average fixed pay rate	3.49%
Weighted average term (Year)	2 years
Notional amount	$ 1,000,000
More Than One Year [Member] | Short [Member]
Cost	(12,252)
Net Estimated Fair Value	$ (8,528)
Weighted average months to expiration (Month)	13 months
Notional amount	$ (1,917,000)
Average fixed pay rate	3.91%
Weighted average term (Year)	5 years 9 months 18 days
Notional amount	$ 1,917,000
More 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