XML 53 R39.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Commitments and Contingent Liabilities - Additional Information (Detail) - USD ($) | Sep. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Loss Contingencies [Line Items] |  |
Notional Amount Of Performance Standby Letters Of Credit | $ 2,900,000 |
Notional Amount Of Commercial Letters Of Credit | 201,000 |
Notional Amount Of Financial Standby Letters Of Credit | 23,000 |
Financial instrument of credit risk | 200,000 | $ 200,000
Unfunded commitment liability | 4,000,000 | $ 4,400,000
Minimum [Member] |  |
Loss Contingencies [Line Items] |  |
Loss Contingency, Estimate of Possible Loss | 0 |
Maximum [Member] |  |
Loss Contingencies [Line Items] |  |
Loss Contingency, Estimate of Possible Loss | $ 7,000,000 |

X
- Definition Notional amount of commercial letters of credit. + References No definition available. + Details
Name: | fcf_NotionalAmountOfCommercialLettersOfCredit
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Notional Amount Of Financial Standby Letters Of Credit + References No definition available. + Details
Name: | fcf_NotionalAmountOfFinancialStandbyLettersOfCredit
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Notional amount of performance standby letters of credit. + References No definition available. + Details
Name: | fcf_NotionalAmountOfPerformanceStandbyLettersOfCredit
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reserve for credit risk of off-balance sheet activities + References No definition available. + Details
Name: | fcf_ReserveForOffBalanceSheetActivities
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties. + 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 210.5-02.25) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 17 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 7 + Details
Name: | us-gaap_FairValueConcentrationOfRiskCommitments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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. + References No definition available. + Details
Name: | us-gaap_LossContingenciesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the estimated amount of loss from the specified contingency as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349 + Details
Name: | us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |