Note 3 - Investment Securities - Securities Available-for-sale (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Securities available for sale, amortized cost	$ 164,345	$ 166,450
Securities available for sale, unrealized gains	2,266	2,345
Securities available for sale, unrealized losses	(1,031)	(3,216)
Securities available for sale	165,580	165,579
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	11,289	1,342
Securities available for sale, unrealized gains	17	3
Securities available for sale, unrealized losses	(10)
Securities available for sale	11,296	1,345
US Treasury Securities [Member]
Securities available for sale, amortized cost	19,987
Securities available for sale, unrealized gains
Securities available for sale, unrealized losses	(16)
Securities available for sale	19,971
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, amortized cost	101,552	111,659
Securities available for sale, unrealized gains	2,203	2,258
Securities available for sale, unrealized losses	(107)	(586)
Securities available for sale	103,648	113,331
Single Issue Trust Preferred Securities [Member]
Securities available for sale, amortized cost	9,367	22,104
Securities available for sale, unrealized gains
Securities available for sale, unrealized losses	(483)	(2,165)
Securities available for sale	8,884	19,939
Mortgage-backed Agency Securities [Member]
Securities available for sale, amortized cost	22,095	31,290
Securities available for sale, unrealized gains	46	66
Securities available for sale, unrealized losses	(415)	(465)
Securities available for sale	21,726	30,891
Equity Securities [Member]
Securities available for sale, amortized cost	55	55
Securities available for sale, unrealized gains		18
Securities available for sale, unrealized losses
Securities available for sale	$ 55	$ 73

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Section 45
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
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