XML 123 R108.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Commitments and Contingent Liabilities (Details Textual) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Commitments and Contingent Liabilities (Additional Textual) [Abstract] |  |
Maximum commitment period to make loans |  | 30 days
Standby letters of credit contractual value | $ 5,800,000 | $ 5,000,000.0
Maximum subscription amount committed in SBIC investment funds | 17,200,000 |
Investment in SBIC funds | $ 10,000,000 |
Commitments and Unused Lines of Credit | Minimum |  |
Commitments and Contingent Liabilities (Textual) [Abstract] |  |
Debt Instrument, Interest Rate, Stated Percentage | 2.25% | 2.25%
Commitments and Unused Lines of Credit | Maximum |  |
Commitments and Contingent Liabilities (Textual) [Abstract] |  |
Debt Instrument, Interest Rate, Stated Percentage | 21.90% | 21.90%

X
- Definition Commitments and Contingent Liabilities (Additional Textual) [Abstract] + References No definition available. + Details
Name: | fmnb_CommitmentsAndContingentLiabilitiesAdditionalTextualAbstract
Namespace Prefix: | fmnb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Commitments and Contingent Liabilities (Textual) [Abstract] + References No definition available. + Details
Name: | fmnb_CommitmentsAndContingentLiabilitiesTextualAbstract
Namespace Prefix: | fmnb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum commitment period to make loans. + References No definition available. + Details
Name: | fmnb_MaximumCommitmentPeriodToMakeLoans
Namespace Prefix: | fmnb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum subscription amount committed in SBIC investment funds. + References No definition available. + Details
Name: | fmnb_MaximumSubscriptionAmountCommittedInSBICInvestmentFunds
Namespace Prefix: | fmnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Standby letters of credit contractual amount. + References No definition available. + Details
Name: | fmnb_StandbyLettersOfCreditContractualAmount
Namespace Prefix: | fmnb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow associated with the purchase of all investments (debt, security, other) during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fmnb_CommitmentsAndUnusedLinesOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |