Note 5 - Derivatives and Other Hedging Instruments - Schedule of Interest Rate Swaps (Details) - Interest Rate Swap [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Notional amount	$ 2,531.8	$ 2,326.5
Average fixed pay rate	2.36%	2.24%
Average receive rate	5.41%	5.45%
Average maturity (Year)	5 years 8 months 12 days	5 years 10 months 24 days
One to Five Years [Member]
Notional amount	$ 1,200.0	$ 500.0
Average fixed pay rate	1.34%	0.84%
Average receive rate	5.45%	5.64%
Average maturity (Year)	3 years 10 months 24 days	2 years 8 months 12 days
More Than Five Years [Member]
Notional amount	$ 1,331.8	$ 1,826.5
Average fixed pay rate	3.28%	2.62%
Average receive rate	5.38%	5.40%
Average maturity (Year)	7 years 4 months 24 days	6 years 9 months 18 days