Note 2 - Investment Securities (Details Textual) $ in Thousands	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Held-to-Maturity, Number of Securities	0
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Ending Balance	$ 0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss	4,000	$ 6,000
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance	$ 0
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	516	498
Debt Securities, Available-for-Sale, Unrealized Loss Position, Percentage	99.00%	98.00%
Collateral Pledged [Member]
Debt Securities, Available-for-Sale, Restricted	$ 949,000	$ 991,000