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Premises and Equipment - Schedule of Future Minimum Rentals (Detail) $ in Thousands | Dec. 31, 2017 USD ($)
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Premises [Member] |
Operating Leased Assets [Line Items] |
2016 | $ 4,459
2017 | 4,106
2018 | 3,348
2019 | 2,929
2020 | 2,646
Thereafter | 12,851
Total | 30,339
Equipment [Member] |
Operating Leased Assets [Line Items] |
2016 | 136
2017 | 78
2018 | 15
2019 | 5
2020 | 0
Thereafter | 0
Total | $ 234

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- Definition Future Minimum Rent Expense Corporate Office Leases Due + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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- Definition Future Minimum Rent Expense Corporate Office Leases Due Current + References No definition available. + Details
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- Definition Future Minimum Rent Expense Corporate Office Leases Due In Five Years + References No definition available. + Details
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Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
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- Definition Future Minimum Rent Expense Corporate Office Leases Due In Four Years + References No definition available. + Details
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Namespace Prefix: | fcf_
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- Definition Future Minimum Rent Expense Corporate Office Leases Due In Three Years + References No definition available. + Details
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Namespace Prefix: | fcf_
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- Definition Future Minimum Rent Expense Corporate Office Leases Due In Two Years + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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- Definition Future Minimum Rent Expense Corporate Office Leases Due Thereafter + References No definition available. + Details
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Namespace Prefix: | fcf_
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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. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
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- Details
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Namespace Prefix: |
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Balance Type: |
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- Details
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Data Type: | na
Balance Type: |
Period Type: |