Note 4 - Loans and Allowance for Loan Losses (Details Textual)	12 Months Ended
Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Loans and Leases Receivable, Net of Deferred Income, Total	$ 525,818,000	$ 493,499,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	317,000	1,137,000
Loans and Leases Receivable, Gross, Total	508,879,000	473,187,000
Off-balance-sheet Commitments to Related Parties	2,000,000.0	7,500,000
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total	6,600,000	5,100,000
Impaired Financing Receivable, Interest Income, Cash Basis Method, Total		0
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	0	0
Troubled Debt Restructuring, Principal Charge-offs	$ 0	$ 0	$ 0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0	0	0
Financing Receivable, Deferred Payments	$ 68,100,000
Financing Receivable, Deferred Payments, Remaining Outstanding	65,300,000
Financing Receivable, Deferred Payments, Resumed	65,100,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance, Total	390,000	$ 466,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses	31,000	12,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	19,000	12,000	$ 2,000
Overall Qualitative Factor [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total	6,000,000.0	3,900,000
Peoples Bancorp, Inc [Member]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	61,000	67,000
Commercial Portfolio Segment [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	82,274,000	45,307,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	(843,000)	0
Loans and Leases Receivable, Gross, Total	$ 81,809,000	45,449,000
Financing Receivable, Modifications, Number of Contracts	2		2
Financing Receivable, Troubled Debt Restructuring	$ 43,000		$ 234,000
Residential Mortgage Segment [Member]
Loans and Leases Receivable, Gross, Total	$ 1,600,000	2,300,000
Amount of Loans Serviced for Others		$ 0
Financing Receivable, Modifications, Number of Contracts		2	1
Financing Receivable, Troubled Debt Restructuring		$ 225,000	$ 241,000
Residential Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts	3
Financing Receivable, Troubled Debt Restructuring	$ 358,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts	1	1	1
Financing Receivable, Troubled Debt Restructuring	$ 250,000	$ 154,000	$ 94,000
Consumer Portfolio Segment [Member]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Troubled Debt Restructuring	$ 294,000	$ 56,000
SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	45,900,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	1,800,000
SBA CARES Act Paycheck Protection Program [Member] \| Commercial Portfolio Segment [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	37,300,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	$ 842,000

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

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Deferred amounts on loans receivable related to loan modification programs offered to financial institution customers affected by COVID-19.

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Deferred amounts that have been resumed on loans receivable related to loan modification programs offered to financial institution customers affected by COVID-19.

+ References

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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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No definition available.

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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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Amount of financing receivable modified as troubled debt restructuring.

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Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent 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.

+ References

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Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring.

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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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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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