Short-term borrowings (Details Textual)	12 Months Ended
Dec. 31, 2020 USD ($) Bank	Dec. 31, 2019 USD ($)
Short Term Debt [Line Items]
Short-term Federal Home Loan Banks advances	$ 66,980,000	$ 42,841,000
Maturity of repurchase agreements	89 days
Securities Sold under Agreements to Repurchase and Other Short Term Borrowings (Additional Textual) [Abstract]
Interest rate, effective percentage	4.60%	4.75%
Domestic Line of Credit
Short Term Debt [Line Items]
Access to lines of credit at domestic banks	$ 35,000,000
Number of domestic banks \| Bank	2
Unsecured revolving line of credit, outstanding balance	$ 0	$ 0
Revolving Credit Facility
Short Term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Revolving Credit Facility \| Farmers National Banc Corp \| Unsecured Debt
Short Term Debt [Line Items]
Unsecured revolving line of credit, outstanding balance	$ 6,500,000
Letter of Credit
Short Term Debt [Line Items]
Unsecured revolving line of credit, outstanding balance	$ 350,000	350,000
Debt Instrument, Interest Rate, Stated Percentage	3.50%
US Treasury and Government Short-term Debt Securities
Short Term Debt [Line Items]
Pledged securities, percentage of repurchase agreement balances	105.00%
Carrying amount of securities sold under repurchase agreement	$ 2,300,000	1,800,000
Pledged
Short Term Debt [Line Items]
Short-term Federal Home Loan Banks advances	$ 0	$ 75,000,000

Maturity period of repurchase agreement.

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Number of domestic bank.

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Pledged securities, percentage of repurchase agreement balances.

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Securities Sold under Agreements to Repurchase and Other Short Term Borrowings (Additional Textual) [Abstract]

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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