Fair Values of Assets and Liabilities - Losses Realized on Assets Measured on Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value Disclosures [Abstract]
Impaired loans	$ (10,806)	$ (3,086)	$ (11,086)	$ (3,742)
Other real estate owned	(241)	(163)	(362)	(3,017)
Total losses	$ (11,047)	$ (3,249)	$ (11,448)	$ (6,759)

Net losses on other real estate owned still held at the end of the period

No definition available.

Name:	fcf_FairValueMeasurementOfAssetsOnNonrecurringBasisNetLossesOnOtherRealEstateOwned
Namespace Prefix:	fcf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration