Note 3 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Less than 12 months, fair value	$ 62,617	$ 50,603
Less than 12 months, unrealized loss	(765)	(316)
12 months or more, fair value	57,672	26,820
12 months or more, unrealized loss	(1,586)	(880)
Fair value	120,289	77,423
Unrealized loss	(2,351)	(1,196)
US Government Agencies Debt Securities [Member]
Less than 12 months, fair value	22,007	10,588
Less than 12 months, unrealized loss	(230)	(46)
12 months or more, fair value	11,972	5,437
12 months or more, unrealized loss	(273)	(97)
Fair value	33,979	16,025
Unrealized loss	(503)	(143)
Collateralized Mortgage Obligations [Member]
Less than 12 months, fair value	93	1,090
Less than 12 months, unrealized loss	(1)	(11)
12 months or more, fair value	1,917	921
12 months or more, unrealized loss	(60)	(26)
Fair value	2,010	2,011
Unrealized loss	(61)	(37)
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, fair value	9,630	28,779
Less than 12 months, unrealized loss	(55)	(236)
12 months or more, fair value	26,559	5,611
12 months or more, unrealized loss	(367)	(72)
Fair value	36,189	34,390
Unrealized loss	(422)	(308)
SBA Pool [Member]
Less than 12 months, fair value	3,284	1,998
Less than 12 months, unrealized loss	(8)	(4)
12 months or more, fair value	3,726	703
12 months or more, unrealized loss	(40)	(9)
Fair value	7,010	2,701
Unrealized loss	(48)	(13)
Corporate Debt Securities [Member]
Less than 12 months, fair value	3,999	1,994
Less than 12 months, unrealized loss	(59)	(6)
12 months or more, fair value	11,645	13,815
12 months or more, unrealized loss	(842)	(675)
Fair value	15,644	15,809
Unrealized loss	(901)	(681)
Asset-backed Securities [Member]
Less than 12 months, fair value	23,604	6,154
Less than 12 months, unrealized loss	(412)	(13)
12 months or more, fair value	1,853	333
12 months or more, unrealized loss	(4)	(1)
Fair value	25,457	6,487
Unrealized loss	$ (416)	$ (14)