Name:	thff_BusinessCombinationFinancialAssetsPurchasedWithCreditDeteriorationContractualReceivablesGross
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of contractual receivables of financial assets purchased with credit deterioration estimated as uncollectible as at the date of business combination.

No definition available.

Name:	thff_BusinessCombinationFinancialAssetsPurchasedWithCreditDeteriorationContractualReceivablesUncollectible
Namespace Prefix:	thff_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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.

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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

No definition available.

Name:	us-gaap_BusinessAcquisitionSharePrice
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Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to financial assets acquired in connection with a business combination for which the initial accounting was incomplete.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Topic 852
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