XML 78 R63.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Statement of Accounting Policies - Additional Information (Detail) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 USD ($) Segment county | Dec. 31, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |
Number of counties in which entity provides services | county | 30 |
Business segments | Segment | 1 |
Equity investments | 20.00% |
Loans past due days | 90 days |
Excess impaired credits | $ 250,000 |
Guaranteed Minimum Death Benefit [Member] |  |
Summary Of Significant Accounting Policies [Line Items] |  |
Other liabilities | $ 3,400,000 | $ 3,500,000

X
- Definition Dollar threshold in which impaired credits are individually evaluated and reviewed. + References No definition available. + Details
Name: | fcf_ExcessImpairedLoanCredit
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Loans Past Due Days + References No definition available. + Details
Name: | fcf_LoansPastDueDays
Namespace Prefix: | fcf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Counties in Which Entity Provides Services + References No definition available. + Details
Name: | fcf_NumberofCountiesinWhichEntityProvidesServices
Namespace Prefix: | fcf_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity investments in which ownership is at least 20% are accounted for using the "equity method" of accounting and are classified as 'Other Assets". + References No definition available. + Details
Name: | fcf_PercentageOfOwnershipInEquityInvestments
Namespace Prefix: | fcf_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Summary Of Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | fcf_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | fcf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before effect of reinsurance, of present value of future benefit to be paid to or on behalf of policyholder and related expense less present value of future net premium receivable under insurance contract. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (g)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6 + Details
Name: | us-gaap_LiabilityForFuturePolicyBenefits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 49 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-49 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-18 + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_GuaranteedInsuranceContractTypeOfBenefitAxis=us-gaap_GuaranteedMinimumDeathBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |