Note 5 - Derivative and Other Hedging Instruments - Schedule of Interest Rate Swaps (Details) - Interest Rate Swap [Member] - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Notional amount	$ 3,943.3	$ 3,516.8
Average fixed pay rate	3.31%	2.78%
Average receive rate	4.25%	4.54%
Average maturity (Year)	5 years 4 months 24 days	5 years 6 months
One to Five Years [Member]
Notional amount	$ 1,922.5	$ 1,450.0
Average fixed pay rate	2.90%	1.69%
Average receive rate	4.24%	4.58%
Average maturity (Year)	3 years 8 months 12 days	3 years 4 months 24 days
More Than Five Years [Member]
Notional amount	$ 2,020.8	$ 2,066.8
Average fixed pay rate	3.69%	3.55%
Average receive rate	4.27%	4.52%
Average maturity (Year)	7 years	7 years