Long-Term Borrowings (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Long-term Debt [Abstract]
Long-term advances	$ 12,876	$ 20,054
Residential mortgage loans	276,900	237,800
Additional borrowing limit	144,000
Long-term investments	$ 2,100
Interest rate	2.70%
Debt interest rate payment description	The debt has a floating rate that is determined quarterly based on the three-month LIBOR
Notes payable	$ 2,200
Debenture maturity date	Dec. 15, 2036
Farmers National Banc Corp
Long-term Debt [Abstract]
Long-term advances		8,000
Fixed-rate constant payment advances
Long-term Debt [Abstract]
Long-term advances	$ 7,876	$ 15,054
Fixed-rate constant payment advances \| Minimum
Long-term Debt [Abstract]
Federal Home Loan Bank interest rate	0.61%	0.61%
Fixed-rate constant payment advances \| Maximum
Long-term Debt [Abstract]
Federal Home Loan Bank interest rate	1.70%	1.70%
Convertible and putable fixed-rate advance
Long-term Debt [Abstract]
Federal Home Loan Bank interest rate	4.45%	4.45%
Long-term advances	$ 5,000	$ 5,000
Fixed-rate advances
Long-term Debt [Abstract]
Retained amount of putable FHLB fixed-rate advances	$ 5,000

Additional federal home loan bank advances to be borrow under collateral pledge.

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- Definition

Federal home loan bank fixed rate putable advances.

+ References

No definition available.

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- Definition

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.

+ References

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Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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- Definition

Discloses the single interest rate [if] applicable to the advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Carrying value as of the balance sheet date of notes payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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