XML 63 R52.htm IDEA: XBRL DOCUMENT
v3.25.3

Schedule of Temporary Impairment Losses, Investments (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 31,438 | $ 274,518
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (740) | (4,693)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 771,082 | 840,467
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (145,477) | (189,855)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 802,520 | 1,114,985
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (146,217) | (194,548)
Debt Securities, Held-to-maturity | 479,915 | 405,639
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 1,135 | 66
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (52,888) | (68,986)
Securities held to maturity, fair value | 428,162 | 336,719
US Government Agencies Debt Securities Commercial |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 31,438 |
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (740) |
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 249,463 |
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (57,624) |
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 280,901 |
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (58,364) |
Residential Mortgage Backed Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 4,759
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (56)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 447,269 | 497,445
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (80,976) | (111,839)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 447,269 | 502,204
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (80,976) | (111,895)
Debt Securities, Held-to-maturity | 301,895 | 266,587
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 508 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (35,800) | (47,564)
Securities held to maturity, fair value | 266,603 | 219,023
US Government-sponsored Enterprises Debt Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 0
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 21,152 | 19,660
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (2,963) | (4,209)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 21,152 | 19,660
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (2,963) | (4,209)
Debt Securities, Held-to-maturity | 23,115 | 22,869
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (2,939) | (4,155)
Securities held to maturity, fair value | 20,176 | 18,714
Obligations of States and Political Subdivisions [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 1,104
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (11)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 27,436 | 28,097
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (2,027) | (3,218)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 27,436 | 29,201
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (2,027) | (3,229)
Debt Securities, Held-to-maturity | 23,740 | 24,193
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (1,396) | (2,246)
Securities held to maturity, fair value | 22,344 | 21,947
Corporate Debt Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 |
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 |
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 22,497 |
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (1,557) |
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 22,497 |
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (1,557) |
US Government Agencies Debt Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Debt Securities, Held-to-maturity | 130,400 |
Securities held to maturity, fair value | 118,200 |
US Government Agencies Residential Mortgage-backed Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 242
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (1)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 2,870 | 3,002
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (325) | (431)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 2,870 | 3,244
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (325) | (432)
Debt Securities, Held-to-maturity | 1,454 | 1,586
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (161) | (220)
Securities held to maturity, fair value | 1,293 | 1,366
Debt Security, Government, Non-US [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 0 | 0
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 395 | 584
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (5) | (16)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total | 395 | 584
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss | (5) | (16)
Debt Securities, Held-to-maturity | 800 | 1,000
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (5) | (16)
Securities held to maturity, fair value | 795 | 984
US Government Agency Debt Securities Commercial [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value |  | 258,712
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss |  | (4,119)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value |  | 274,358
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss |  | (68,212)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total |  | 533,070
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss |  | (72,331)
Debt Securities, Held-to-maturity | 128,911 | 89,404
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 627 | 66
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (12,587) | (14,785)
Securities held to maturity, fair value | $ 116,951 | 74,685
Corporate Securities [Member] |  |
Schedule of Unrealized Losses and Estimated Fair Values [Line Items] |  |
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value |  | 9,701
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss |  | (506)
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value |  | 17,321
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss |  | (1,930)
Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total |  | 27,022
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss |  | $ (2,436)

X
- Definition Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value + References No definition available. + Details
Name: | fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Schedule of Unrealized Losses and Estimated Fair Values [Line Items] + References No definition available. + Details
Name: | fcf_ScheduleOfUnrealizedLossesAndEstimatedFairValuesLineItems
Namespace Prefix: | fcf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-7A Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-14 + Details
Name: | us-gaap_HeldToMaturitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 28 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 6: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fcf_USGovernmentAgenciesDebtSecuritiesCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fcf_USGovernmentAgencyDebtSecuritiesResidentialDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fcf_USGovernmentAgencyDebtSecuritiesCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=fcf_CorporateSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |