Note 4 - Available for Sale Securities - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Less Than 12 Months Fair Value	$ 36,273	$ 31,275
Less Than 12 Months Unrealized Losses	(903)	(255)
12 Months or More Fair Value	13,711	12,180
12 Months or More Unrealized Losses	(511)	(289)
Total Fair Value	49,984	43,455
Total Unrealized Losses	(1,414)	(544)
US Government Corporations and Agencies Securities [Member]
Less Than 12 Months Fair Value	1,383	235
Less Than 12 Months Unrealized Losses	(6)	(2)
12 Months or More Fair Value	138
12 Months or More Unrealized Losses	(1)
Total Fair Value	1,521	235
Total Unrealized Losses	(7)	(2)
US States and Political Subdivisions Debt Securities [Member]
Less Than 12 Months Fair Value	4,336	3,180
Less Than 12 Months Unrealized Losses	(78)	(23)
12 Months or More Fair Value	2,598	2,660
12 Months or More Unrealized Losses	(71)	(46)
Total Fair Value	6,934	5,840
Total Unrealized Losses	(149)	(69)
Collateralized Mortgage Backed Securities [Member]
Less Than 12 Months Fair Value	22,561	22,685
Less Than 12 Months Unrealized Losses	(640)	(213)
12 Months or More Fair Value	10,975	9,270
12 Months or More Unrealized Losses	(439)	(242)
Total Fair Value	33,536	31,955
Total Unrealized Losses	(1,079)	(455)
Certificates of Deposit [Member]
Less Than 12 Months Fair Value	3,647	2,492
Less Than 12 Months Unrealized Losses	(103)	(9)
12 Months or More Fair Value
12 Months or More Unrealized Losses
Total Fair Value	3,647	2,492
Total Unrealized Losses	(103)	(9)
Corporate Debt Securities [Member]
Less Than 12 Months Fair Value	4,346	2,683
Less Than 12 Months Unrealized Losses	(76)	(8)
12 Months or More Fair Value		250
12 Months or More Unrealized Losses		(1)
Total Fair Value	4,346	2,933
Total Unrealized Losses	$ (76)	$ (9)