-- None. No documentation exists for this element. --

No definition available.

Name:	thff_FinancingReceivableAbstract
Namespace Prefix:	thff_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Recorded Investment in financing receivables.

+ References

No definition available.

+ Details

Name:	thff_FinancingReceivableRecordedInvestment
Namespace Prefix:	thff_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossAdditionalInformationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_NotesReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_UnallocatedFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityAxis=us-gaap_ReceivablesAcquiredWithDeterioratedCreditQualityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Loan Losses (Details 1) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Ending Balance Attributable to Loans
Individually evaluated for impairment	$ 857		$ 1,159
Collectively evaluated for impairment	18,069		18,600
Ending Balance	19,074	$ 19,504	19,946	$ 19,925	$ 19,861	$ 18,839
Loans
Individually evaluated for impairment	10,644		9,725
Collectively evaluated for impairment	1,811,581		1,754,444
Total	1,827,474		1,769,790
Commercial Portfolio Segment [Member]
Ending Balance Attributable to Loans
Individually evaluated for impairment	748		953
Collectively evaluated for impairment	9,369		10,342
Ending Balance	10,265	10,244	11,482	12,089	10,931	10,915
Loans
Individually evaluated for impairment	10,073		8,823
Collectively evaluated for impairment	1,076,103		1,037,086
Total	1,089,936		1,050,001
Residential Portfolio Segment [Member]
Ending Balance Attributable to Loans
Individually evaluated for impairment	109		206
Collectively evaluated for impairment	1,469		1,628
Ending Balance	1,578	1,595	1,834	1,894	1,760	1,374
Loans
Individually evaluated for impairment	571		902
Collectively evaluated for impairment	429,413		443,224
Total	431,473		445,655
Consumer Portfolio Segment [Member]
Ending Balance Attributable to Loans
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	5,619		4,945
Ending Balance	5,619	5,258	4,945	4,948	4,678	4,370
Loans
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	306,065		274,134
Total	306,065		274,134
Unallocated
Ending Balance Attributable to Loans
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	1,612		1,685
Ending Balance	1,612	$ 2,407	1,685	$ 994	$ 2,492	$ 2,180
Receivables Acquired with Deteriorated Credit Quality [Member]
Ending Balance Attributable to Loans
Financing Receivable, Allowance for Credit Losses	148		187
Loans
Financing Receivable, Net	5,249		5,621
Receivables Acquired with Deteriorated Credit Quality [Member] \| Commercial Portfolio Segment [Member]
Ending Balance Attributable to Loans
Financing Receivable, Allowance for Credit Losses	148		187
Loans
Financing Receivable, Net	3,760		4,092
Receivables Acquired with Deteriorated Credit Quality [Member] \| Residential Portfolio Segment [Member]
Ending Balance Attributable to Loans
Financing Receivable, Allowance for Credit Losses	0		0
Loans
Financing Receivable, Net	1,489		1,529
Receivables Acquired with Deteriorated Credit Quality [Member] \| Consumer Portfolio Segment [Member]
Ending Balance Attributable to Loans
Financing Receivable, Allowance for Credit Losses	0		0
Loans
Financing Receivable, Net	0		0
Receivables Acquired with Deteriorated Credit Quality [Member] \| Unallocated
Ending Balance Attributable to Loans
Financing Receivable, Allowance for Credit Losses	$ 0		$ 0