Note 3 - Investment Securities (Details Textual) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Held-to-Maturity, Allowance for Credit Loss	$ 1	$ 1	$ 1	$ 1
Total	4,516,389	4,849,363
Asset Pledged as Collateral [Member] | Public Deposits and Short-term Borrowed Funds [Member]
Total	$ 2,339,848	$ 2,034,706