Note 6 - Securities Sold Under Agreements to Repurchase - Securities Sold Under Agreement to Repurchase (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Securities sold under agreements to repurchase	$ 228,618	$ 229,734
Average daily balance during the period	216,674	204,334
Maximum daily balance during the period	$ 247,056	$ 269,324
Securities Sold under Agreements to Repurchase [Member]
Average interest rate at end of period	3.30%	3.17%
Average interest rate during the period	3.06%	1.33%