Note 3 - Securities - Available for Sale Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Total, fair value	$ 44,101	$ 177,735
Total, unrealized loss	136	659
Less than 12 months, fair value	34,015	116,198
Less than 12 months, unrealized loss	43	352
12 months or more, fair value	10,086	61,537
12 months or more, unrealized loss	93	307
US Treasury Securities [Member]
Total, fair value	9,998	14,987
Total, unrealized loss	0	5
Less than 12 months, fair value	9,998	14,987
Less than 12 months, unrealized loss	0	5
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Total, fair value	14,468	69,095
Total, unrealized loss	32	219
Less than 12 months, fair value	13,013	31,779
Less than 12 months, unrealized loss	7	44
12 months or more, fair value	1,455	37,316
12 months or more, unrealized loss	25	175
Collateralized Mortgage Backed Securities [Member]
Total, fair value	9,652	89,391
Total, unrealized loss	30	393
Less than 12 months, fair value	9,652	66,324
Less than 12 months, unrealized loss	30	266
12 months or more, fair value	0	23,067
12 months or more, unrealized loss	0	127
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	1,352	4,262
Total, unrealized loss	6	42
Less than 12 months, fair value	1,352	3,108
Less than 12 months, unrealized loss	6	37
12 months or more, fair value	0	1,154
12 months or more, unrealized loss	0	$ 5
Corporate Debt Securities [Member]
Total, fair value	8,631
Total, unrealized loss	68
Less than 12 months, fair value	0
Less than 12 months, unrealized loss	0
12 months or more, fair value	8,631
12 months or more, unrealized loss	$ 68