XML 53 R44.htm IDEA: XBRL DOCUMENT
v3.23.3

Fair Value - Quantitative information about recurring and non-recurring Level 3 fair value measurements (Details) $ in Thousands | Sep. 30, 2023 USD ($) | Dec. 31, 2022 USD ($)
--- | --- | ---
state and municipal obligations | Level 3 |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Fair Value | $ 1,180 | $ 1,545
state and municipal obligations | Minimum | Discount rate |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Range of Inputs (percent) | 0.0404 | 0.0373
state and municipal obligations | Maximum | Discount rate |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Range of Inputs (percent) | 0.0444 | 0.0444
Collateralized debt obligations | Discount rate |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Range of Inputs (percent) | 0.0722 | 0.0534
Collateralized debt obligations | Level 3 |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Fair Value | $ 3,024 | $ 2,986
Collateral dependent loans | Level 3 |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Fair Value | $ 1,812 | $ 4,477
Collateral dependent loans | Minimum | Discount rate |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Range of Inputs (percent) | 0.0000 | 0.0000
Collateral dependent loans | Maximum | Discount rate |  |
Fair Value Measurement Inputs and Valuation Techniques |  |
Range of Inputs (percent) | 0.5000 | 0.5000

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Value of input used to measure 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 -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
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: |

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

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