Note 3 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Less than 12 months, fair value	$ 61,128	$ 9,272
Less than 12 months, unrealized loss	(1,371)	(71)
12 months or more, fair value	4,193	7,474
12 months or more, unrealized loss	(26)	(45)
Total, fair value	65,321	16,746
Total, unrealized loss	(1,397)	(116)
US Government Agencies Debt Securities [Member]
Less than 12 months, fair value	1,988	1,996
Less than 12 months, unrealized loss	(12)	(40)
12 months or more, fair value
12 months or more, unrealized loss
Total, fair value	1,988	1,996
Total, unrealized loss	(12)	(40)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Less than 12 months, fair value	7,598	1,547
Less than 12 months, unrealized loss	(121)	(6)
12 months or more, fair value
12 months or more, unrealized loss
Total, fair value	7,598	1,547
Total, unrealized loss	(121)	(6)
Collateralized Mortgage Obligations [Member]
Less than 12 months, fair value	7,899	1,515
Less than 12 months, unrealized loss	(128)	(4)
12 months or more, fair value	2,053	4,845
12 months or more, unrealized loss	(2)	(6)
Total, fair value	9,952	6,360
Total, unrealized loss	(130)	(10)
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, fair value	35,270	1,705
Less than 12 months, unrealized loss	(1,009)	(11)
12 months or more, fair value	1,655	1,641
12 months or more, unrealized loss	(9)	(27)
Total, fair value	36,925	3,346
Total, unrealized loss	(1,018)	(38)
Corporate Debt Securities [Member]
Less than 12 months, fair value	8,373	2,509
Less than 12 months, unrealized loss	(101)	(10)
12 months or more, fair value	485	988
12 months or more, unrealized loss	(15)	(12)
Total, fair value	8,858	3,497
Total, unrealized loss	$ (116)	$ (22)