Note 4 - Available for Sale Securities - Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Less Than 12 Months Fair Value	$ 584	$ 1,730
Less Than 12 Months Unrealized Losses	(6)	(26)
12 Months or More Fair Value	26,397	35,303
12 Months or More Unrealized Losses	(364)	(839)
Total Fair Value	26,981	37,033
Total Unrealized Losses	(370)	(865)
US Government Corporations and Agencies Securities [Member]
Less Than 12 Months Fair Value	584	175
Less Than 12 Months Unrealized Losses	(6)
12 Months or More Fair Value	95	113
12 Months or More Unrealized Losses
Total Fair Value	679	288
Total Unrealized Losses	(6)
US States and Political Subdivisions Debt Securities [Member]
Less Than 12 Months Fair Value
Less Than 12 Months Unrealized Losses
12 Months or More Fair Value	4,800	6,142
12 Months or More Unrealized Losses	(52)	(103)
Total Fair Value	4,800	6,142
Total Unrealized Losses	(52)	(103)
Collateralized Mortgage Backed Securities [Member]
Less Than 12 Months Fair Value		1,171
Less Than 12 Months Unrealized Losses		(24)
12 Months or More Fair Value	19,244	24,725
12 Months or More Unrealized Losses	(283)	(628)
Total Fair Value	19,244	25,896
Total Unrealized Losses	(283)	(652)
Certificates of Deposit [Member]
Less Than 12 Months Fair Value
Less Than 12 Months Unrealized Losses
12 Months or More Fair Value	1,227	1,195
12 Months or More Unrealized Losses	(23)	(55)
Total Fair Value	1,227	1,195
Total Unrealized Losses	(23)	(55)
Corporate Debt Securities [Member]
Less Than 12 Months Fair Value		384
Less Than 12 Months Unrealized Losses		(2)
12 Months or More Fair Value	1,031	3,128
12 Months or More Unrealized Losses	(6)	(53)
Total Fair Value	1,031	3,512
Total Unrealized Losses	$ (6)	$ (55)