Note 4 - Loans and Allowance for Loan Losses - Allowance for Loan Losses and the Recorded Investment of Loans Based on Impairment Method (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Individually evaluated for impairment	$ 92	$ 94
Collectively evaluated for impairment	7,904	7,405
Total ending allowance balance	7,996	7,499	$ 7,315	$ 7,699
Loans individually evaluated for impairment	16,227	18,108
Loans collectively evaluated for impairment	751,838	751,211
Total ending loans balance	768,065	769,319
Residential Portfolio Segment [Member]
Individually evaluated for impairment
Collectively evaluated for impairment	2,059	1,470
Total ending allowance balance	2,059	1,470	1,392	939
Loans individually evaluated for impairment	1,679	1,420
Loans collectively evaluated for impairment	303,514	307,743
Total ending loans balance	305,193	309,163
Commercial Real Estate Portfolio Segment [Member]
Individually evaluated for impairment	92	94
Collectively evaluated for impairment	2,331	2,884
Total ending allowance balance	2,423	2,978	2,729	4,315
Loans individually evaluated for impairment	6,356	7,333
Loans collectively evaluated for impairment	205,331	206,113
Total ending loans balance	211,687	213,446
Commercial and Industrial Portfolio Segment [Member]
Individually evaluated for impairment
Collectively evaluated for impairment	1,373	1,024
Total ending allowance balance	1,373	1,024	1,360	907
Loans individually evaluated for impairment	8,192	9,154
Loans collectively evaluated for impairment	105,372	97,935
Total ending loans balance	113,564	107,089
Consumer Portfolio Segment [Member]
Individually evaluated for impairment
Collectively evaluated for impairment	2,141	2,027
Total ending allowance balance	2,141	2,027	$ 1,834	$ 1,538
Loans individually evaluated for impairment		201
Loans collectively evaluated for impairment	137,621	139,420
Total ending loans balance	$ 137,621	$ 139,621

A valuation allowance for financing receivables that are expected to be uncollectible.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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