Note 4 - Loans and Allowance for Loan Losses (Details Textual)	12 Months Ended
Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	$ 1,095,000	$ 1,041,000
Loans and Leases Receivable, Gross, Total	439,855,000	414,617,000
Off-balance-sheet Commitments to Related Parties	2,600,000	2,800,000
Impaired Financing Receivable, Interest Income, Cash Basis Method, Total	0	0	$ 0
Loans and Leases Receivable, Impaired, Commitment to Lend	0	0
Financing Receivable, Modifications, Number of Contracts			0
Troubled Debt Restructuring, Principal Charge-offs	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0	0
Troubled Debt Restructuring, Specific Allowance	$ 0	$ 0	$ 0
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance, Total	519,000	625,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses	0	2,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	2,000	2,000	$ 0
Classified Loans [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total	333,000	506,000
Overall Qualitative Factor [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total	3,100,000	2,600,000
Residential Mortgage Segment [Member]
Loans and Leases Receivable, Gross, Total	2,700,000	3,200,000
Amount of Loans Serviced for Others	$ 111,000	$ 117,000
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Recorded Investment	$ 241,000	$ 65,000
Commercial Portfolio Segment [Member]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total		2,000
Loans and Leases Receivable, Gross, Total	$ 36,417,000	34,203,000
Financing Receivable, Modifications, Number of Contracts	2
Financing Receivable, Modifications, Recorded Investment	$ 234,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts	1
Financing Receivable, Modifications, Recorded Investment	$ 94,000
Peoples Bancorp, Inc [Member]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	$ 70,000	$ 87,000

The amount of mortgage loans serviced for the benefit of others.

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Amount of off-balance-sheet commitments (including commitments to make loans, unused lines of credit and letters of credit) to related parties.

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Represents the amount of principal charge-offs for troubled debt restructuring.

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Amount of increase (decrease) of allowance reserve for credit loss.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Amount of reduction in the reserve for loans impairments as a result of current information and events which result in it being probable that estimated cash flows will be significantly higher than previously expected or because actual cash flows are significantly greater than cash flows previously expected for loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Number of financing receivables that have been modified by troubled debt restructurings.

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The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

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Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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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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Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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