Note 8 - Loans Disaggregated by Impairment Method (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	$ 9,015	$ 8,834	$ 8,037	$ 7,841
Allowance for loan losses - individually evaluated for impairment	1,709	1,664
Allowance for loan losses - collectively evaluated for impairment	6,745	6,709
Loans and leases receivable	804,308	785,208
Loans - individually evaluated for impairment	12,782	16,482
Loans - collectively evaluated for impairment	791,526	768,726
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	3,083	3,092	2,829	2,711
Allowance for loan losses - individually evaluated for impairment	1,572	1,461
Allowance for loan losses - collectively evaluated for impairment	1,511	1,631
Loans and leases receivable	165,381	162,452
Loans - individually evaluated for impairment	3,537	7,128
Loans - collectively evaluated for impairment	161,844	155,324
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	602	551	557	563
Allowance for loan losses - individually evaluated for impairment	0	0
Allowance for loan losses - collectively evaluated for impairment	602	551
Loans and leases receivable	54,717	50,135
Loans - collectively evaluated for impairment	54,717	50,135
Commercial Portfolio Segment [Member] \| Secured by Commercial Real Estate [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	2,829	2,824	2,431	2,410
Allowance for loan losses - individually evaluated for impairment	62	101
Allowance for loan losses - collectively evaluated for impairment	2,767	2,723
Loans and leases receivable	313,436	308,590
Loans - individually evaluated for impairment	5,941	6,083
Loans - collectively evaluated for impairment	307,495	302,507
Commercial Portfolio Segment [Member] \| Secured by Residential Real Estate [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	743	754	835	816
Allowance for loan losses - individually evaluated for impairment	75	97
Allowance for loan losses - collectively evaluated for impairment	668	657
Loans and leases receivable	72,211	68,581
Loans - individually evaluated for impairment	1,833	1,740
Loans - collectively evaluated for impairment	70,378	66,841
State and Political Subdivisions Portfolio Segment [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	190	153	121	114
Allowance for loan losses - individually evaluated for impairment	0	0
Allowance for loan losses - collectively evaluated for impairment	190	153
Loans and leases receivable	47,552	43,737
Loans - individually evaluated for impairment	0	0
Loans - collectively evaluated for impairment	47,552	43,737
Retail Portfolio Segment [Member] \| Consumer Loans [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	166	164	61	57
Allowance for loan losses - individually evaluated for impairment	0	0
Allowance for loan losses - collectively evaluated for impairment	166	164
Loans and leases receivable	6,661	6,785
Loans - individually evaluated for impairment	75	77
Loans - collectively evaluated for impairment	6,586	6,708
Retail Portfolio Segment [Member] \| Family Residential Mortgages [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	500	497	512	444
Allowance for loan losses - collectively evaluated for impairment	500	497
Loans and leases receivable	67,831	67,453
Loans - individually evaluated for impairment	1,247	1,268
Loans - collectively evaluated for impairment	66,584	66,185
Retail Portfolio Segment [Member] \| Home Equity Loans and Lines [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	341	338	381	357
Allowance for loan losses - individually evaluated for impairment	0	5
Allowance for loan losses - collectively evaluated for impairment	341	333
Loans and leases receivable	76,519	77,475
Loans - individually evaluated for impairment	149	186
Loans - collectively evaluated for impairment	76,370	77,289
Unallocated Financing Receivables [Member]
Credit Losses Related To Financing Receivables Current And Noncurrent [Line Items]
Allowance for loan losses	$ 561	$ 461	$ 310	$ 369

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

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