XML 124 R110.htm IDEA: XBRL DOCUMENT
v3.20.4

Fair Values of Financial Instruments - Fair Value Measurements of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | $ 1,919,119 | $ 1,790,025
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Interest rate swap asset | 0 | 0
Interest rate swap liability | 0 | 0
Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 1,916,640 | 1,787,132
Interest rate swap asset | 74,335 | 27,855
Interest rate swap liability | 76,353 | 29,299
Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 2,479 | 2,893
Interest rate swap asset | 0 | 0
Interest rate swap liability | 0 | 0
Recurring | Interest rate swap liability |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap liability | 76,353 | 29,299
Recurring | U.S. Government-sponsored agency securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 2,430 | 38,875
Recurring | State and municipal |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 1,257,885 | 899,796
Recurring | U.S. Government-sponsored mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 654,669 | 851,323
Recurring | Corporate obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 4,135 | 31
Recurring | Interest rate swap asset |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap asset | 74,335 | 27,855
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swap liability |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap liability | 0 | 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government-sponsored agency securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | State and municipal |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government-sponsored mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swap asset |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap asset | 0 | 0
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap liability |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap liability | 76,353 | 29,299
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government-sponsored agency securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 2,430 | 38,875
Recurring | Significant Other Observable Inputs (Level 2) | State and municipal |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 1,255,441 | 896,938
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government-sponsored mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 654,665 | 851,319
Recurring | Significant Other Observable Inputs (Level 2) | Corporate obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 4,104 | 0
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap asset |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap asset | 74,335 | 27,855
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swap liability |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap liability | 0 | 0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government-sponsored agency securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 0 | 0
Recurring | Significant Unobservable Inputs (Level 3) | State and municipal |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 2,444 | 2,858
Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government-sponsored mortgage-backed securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 4 | 4
Recurring | Significant Unobservable Inputs (Level 3) | Corporate obligations |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Investment securities available for sale | 31 | 31
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swap asset |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate swap asset | $ 0 | $ 0

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=frme_InterestRateSwapLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=frme_InterestRateSwapAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |