XML 64 R27.htm IDEA: XBRL DOCUMENT v2.4.1.9
Allowance for Loan Losses (Details 2) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Unpaid Principal Balance      
TOTAL $ 16,658us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance   $ 16,394us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Recorded Investment      
Impaired Financing Receivable, with Related Allowance, Recorded Investment 12,787us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment   11,477us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Fair value 14,851us-gaap_ImpairedFinancingReceivableRecordedInvestment   14,606us-gaap_ImpairedFinancingReceivableRecordedInvestment
Allowance For Loan Losses Allocated      
TOTAL 1,557thff_ImpairedFinancingReceivableLoanLossesAlocated   1,911thff_ImpairedFinancingReceivableLoanLossesAlocated
Average Recorded Investment      
TOTAL 14,730us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 17,918us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 16,732us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Interest Income Recognized      
TOTAL 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 0us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Cash Basis Interest Income Recognized      
TOTAL 0us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod 0us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod 0us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod
Commercial & Industrial      
Unpaid Principal Balance      
With no related allowance recorded: 251us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  1,200us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
With an allowance recorded: 8,824us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  7,388us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Recorded Investment      
With no related allowance recorded: 251us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  926us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 7,017us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  5,874us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Fair value 6,442us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  4,818us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
With an allowance recorded: 575thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
  1,056thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Average Recorded Investment      
With no related allowance recorded: 589us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
1,906us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
2,589us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
With an allowance recorded: 6,446us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
8,085us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
6,177us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_CommercialAndIndustrialReceivablesMember
Farmland      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_FarmlandMember
Non Farm, Non Residential      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
With an allowance recorded: 6,482us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  6,654us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 6,482us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  6,654us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Fair value 5,597us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  5,901us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
With an allowance recorded: 885thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
  753thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
104us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
58us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
With an allowance recorded: 6,568us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
6,740us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
6,698us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_NonFarmNonResidentialReceivablesMember
Agriculture      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
   
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_AgricultureReceivablesMember
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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Cash Basis Interest Income Recognized      
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All Other Commercial      
Unpaid Principal Balance      
With no related allowance recorded: 256us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
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Recorded Investment      
With no related allowance recorded: 256us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
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  827us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
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Fair value 483us-gaap_ImpairedFinancingReceivableRecordedInvestment
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  725us-gaap_ImpairedFinancingReceivableRecordedInvestment
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Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
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  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
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With an allowance recorded: 97thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
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  102thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
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Average Recorded Investment      
With no related allowance recorded: 274us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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58us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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1,046us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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1,112us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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First Liens      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
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  33us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
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Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
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  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
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  33us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
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Fair value 265us-gaap_ImpairedFinancingReceivableRecordedInvestment
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  33us-gaap_ImpairedFinancingReceivableRecordedInvestment
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Allowance For Loan Losses Allocated      
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With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
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  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
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Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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5us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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With an allowance recorded: 149us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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37us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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35us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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Interest Income Recognized      
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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Cash Basis Interest Income Recognized      
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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Home Equity      
Unpaid Principal Balance      
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Recorded Investment      
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  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
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Allowance For Loan Losses Allocated      
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Average Recorded Investment      
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
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Interest Income Recognized      
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
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Cash Basis Interest Income Recognized      
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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Junior Liens      
Unpaid Principal Balance      
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With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
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= us-gaap_SecondMortgageMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_SecondMortgageMember
Multifamily      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_MultifamilyMember
All Other Residential      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherResidentialReceivablesMember
Motor Vehicle      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_AutomobileLoanMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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All Other Consumer      
Unpaid Principal Balance      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Recorded Investment      
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/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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  0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Impaired Financing Receivable, with Related Allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
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  0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Fair value 0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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  0us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Allowance For Loan Losses Allocated      
With no related allowance recorded: 0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
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  0thff_ImpairedFinancingReceivableWithNoRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: 0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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  0thff_ImpairedFinancingReceivableWithRelatedAllowanceForLoanLossesAllocated
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Average Recorded Investment      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= thff_OtherConsumerReceivablesMember
Cash Basis Interest Income Recognized      
With no related allowance recorded: 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
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0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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With an allowance recorded: $ 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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$ 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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$ 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeCashBasisMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
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