Note 2 - Securities - Available for Sale Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Total, fair value	$ 230,784	$ 77,323
Total, unrealized loss	3,587	162
Less than 12 months, fair value	225,417	76,060
Less than 12 months, unrealized loss	3,564	143
12 months or more, fair value	5,367	1,263
12 months or more, unrealized loss	23	19
US Treasury Securities [Member]
Total, fair value	30,046
Total, unrealized loss	106
Less than 12 months, fair value	30,046
Less than 12 months, unrealized loss	106
12 months or more, fair value	0
12 months or more, unrealized loss	0
US Government-sponsored Enterprises Debt Securities [Member]
Total, fair value	56,948	21,237
Total, unrealized loss	677	45
Less than 12 months, fair value	55,779	19,974
Less than 12 months, unrealized loss	660	26
12 months or more, fair value	1,169	1,263
12 months or more, unrealized loss	17	19
Collateralized Mortgage Backed Securities [Member]
Total, fair value	123,513	46,640
Total, unrealized loss	2,369	105
Less than 12 months, fair value	119,315	46,640
Less than 12 months, unrealized loss	2,363	105
12 months or more, fair value	4,198	0
12 months or more, unrealized loss	6	0
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	18,278	3,456
Total, unrealized loss	434	2
Less than 12 months, fair value	18,278	3,456
Less than 12 months, unrealized loss	434	2
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
Corporate Debt Securities [Member]
Total, fair value	1,999	5,990
Total, unrealized loss	1	10
Less than 12 months, fair value	1,999	5,990
Less than 12 months, unrealized loss	1	10
12 months or more, fair value	0	0
12 months or more, unrealized loss	$ 0	$ 0