Note 3 - Investment Securities (Details Textual) Pure in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale, Holding Greater than 10 Percent of Equity	0		0
Debt Securities, Available-for-Sale, Realized Gain (Loss)	$ 0	$ 0
Accrued Investment Income Receivable	2,100		$ 2,400
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0		0
Asset Pledged as Collateral [Member]
Debt Securities, Available-for-Sale, Restricted	$ 332,500		$ 157,000