Note 2 - Securities - Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Securities available for sale, amortized cost	$ 372,909	$ 375,183
Securities available for sale, gross unrealized gains	1	1
Securities available for sale, gross unrealized losses	(43,824)	(48,615)
Investment securities available for sale, at fair value	329,086	326,569
Securities available for sale, gross unrealized losses	(43,824)	(48,615)
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, amortized cost	119,761	119,990
Securities available for sale, gross unrealized gains	1	0
Securities available for sale, gross unrealized losses	(17,852)	(21,940)
Investment securities available for sale, at fair value	101,910	98,050
Securities available for sale, gross unrealized losses	(17,852)	(21,940)
US Treasury Securities [Member]
Securities available for sale, amortized cost	2,472
Securities available for sale, gross unrealized gains	0
Securities available for sale, gross unrealized losses	(82)
Investment securities available for sale, at fair value	2,390
Securities available for sale, gross unrealized losses	(82)
US Treasury Notes Securities [Member]
Securities available for sale, amortized cost		2,469
Securities available for sale, gross unrealized gains		0
Securities available for sale, gross unrealized losses		(105)
Investment securities available for sale, at fair value		2,364
Securities available for sale, gross unrealized losses		(105)
International Agency Bonds [Member]
Securities available for sale, amortized cost	1,957	1,955
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(212)	(253)
Investment securities available for sale, at fair value	1,745	1,702
Securities available for sale, gross unrealized losses	(212)	(253)
Corporate Debt Securities [Member]
Securities available for sale, amortized cost	60,648	60,700
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	(5,531)	(5,201)
Investment securities available for sale, at fair value	55,117	55,499
Securities available for sale, gross unrealized losses	(5,531)	(5,201)
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale, amortized cost	87,398	88,930
Securities available for sale, gross unrealized gains	0	1
Securities available for sale, gross unrealized losses	(12,452)	(13,283)
Investment securities available for sale, at fair value	74,946	75,648
Securities available for sale, gross unrealized losses	(12,452)	(13,283)
Mortgage-Backed Securities, Issued by Private Enterprises [Member]
Securities available for sale, amortized cost	100,673	101,139
Securities available for sale, gross unrealized gains		0
Securities available for sale, gross unrealized losses	(7,695)	(7,833)
Investment securities available for sale, at fair value	92,978	93,306
Securities available for sale, gross unrealized losses	$ (7,695)	$ (7,833)