Note 6 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Securities sold under agreements to repurchase	$ 164,082,000	$ 194,340,000
Average daily balance during the period	211,680,000	200,499,000
Maximum daily balance during the period	$ 269,324,000	$ 235,577,000
Securities Sold under Agreements to Repurchase [Member]
Average interest rate at end of period	0.74%	0.75%
Average interest rate during the period	1.22%	0.15%