XML 55 R45.htm IDEA: XBRL DOCUMENT
v3.19.2

Investment Securities - Investments in Debt and Equity Securities Reported Less than Historical Cost (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Schedule of Investments [Line Items] |  |
Fair value | $ 156,285 | $ 932,577
Investments reported at less than historical cost |  |
Schedule of Investments [Line Items] |  |
Historical cost | 157,406 | 951,571
Fair value | 156,285 | 932,577
Gross unrealized losses | $ 1,121 | $ 18,994
Percent of the Corporation's investment portfolio | 7.50% | 57.10%

X
- Definition Investment Historical Cost + References No definition available. + Details
Name: | frme_InvestmentHistoricalCost
Namespace Prefix: | frme_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of Total Investment Portfolio, Fair Value + References No definition available. + Details
Name: | frme_PercentageOfTotalInvestmentPortfolioFairValue
Namespace Prefix: | frme_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Securities Continuous Unrealized Loss Position, Accumulated Loss + References No definition available. + Details
Name: | frme_SecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | frme_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Securities, Continuous Unrealized Loss Position, Fair Value + References No definition available. + Details
Name: | frme_SecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | frme_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_ScheduleOfInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=frme_InvestmentsInDebtAndEquitySecuritiesReportedAtLessThanHistoricalCostMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |