Subordinated Debentures Subordinated Debentures, Additional Information (Details) $ in Millions |
Mar. 31, 2026
USD ($)
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| Debt Instrument [Line Items] | |
| Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net | $ 0.8 |
| First Commonwealth Capital Trust II [Member] | |
| Debt Instrument [Line Items] | |
| Debt Issuance Costs, Gross | 0.5 |
| First Commonwealth Bank 2033 [Member] | |
| Debt Instrument [Line Items] | |
| Subordinated Debt Par Amount | 50.0 |
| Debt Issuance Costs, Gross | 1.1 |
| First Commonwealth Capital Trust III [Member] | |
| Debt Instrument [Line Items] | |
| Debt Issuance Costs, Gross | 0.6 |
| First Commonwealth Financial Corporation | |
| Debt Instrument [Line Items] | |
| Subordinated Debt Par Amount | $ 6.0 |
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- Definition Subordinated Debt Par Amount No definition available.
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- 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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of unamortized debt discount (premium) and debt issuance costs. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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