Note 3 - Debt Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Securities available for sale, amortized cost	$ 181,529	$ 295,045
Securities available for sale, unrealized gains	6	29
Securities available for sale, unrealized losses	(15,288)	(14,113)
Securities available for sale, fair value	166,247	280,961	[1]
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	5,750	5,750
Securities available for sale, unrealized gains	0	0
Securities available for sale, unrealized losses	0	(1)
Securities available for sale, fair value	5,750	5,749
US Treasury Securities [Member]
Securities available for sale, amortized cost	36,384	146,653
Securities available for sale, unrealized gains	2	16
Securities available for sale, unrealized losses	(62)	(843)
Securities available for sale, fair value	36,324	145,826
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, amortized cost	18,325	19,528
Securities available for sale, unrealized gains	4	11
Securities available for sale, unrealized losses	(217)	(162)
Securities available for sale, fair value	18,112	19,377
Corporate Debt Securities [Member]
Securities available for sale, amortized cost	28,574	28,566
Securities available for sale, unrealized gains	0	0
Securities available for sale, unrealized losses	(1,658)	(1,485)
Securities available for sale, fair value	26,916	27,081
Mortgage-backed Agency Securities [Member]
Securities available for sale, amortized cost	92,496	94,548
Securities available for sale, unrealized gains	0	2
Securities available for sale, unrealized losses	(13,351)	(11,622)
Securities available for sale, fair value	$ 79,145	$ 82,928

[1] Derived from audited financial statements