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Other Long-term Debt - Additional Information (Detail) (FHLB [Member], USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012
Loan advance amount | 7.5
LIBOR [Member] |
Floating rate Period | 3 month

X
- Definition Floating Interest Rate Period + References No definition available. + Details
Name: | fcf_FloatingInterestRatePeriod
Namespace Prefix: | fcf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Term loan advances aggregate amount. + References No definition available. + Details
Name: | fcf_TermLoanAdvancesAggregateAmount
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant