| **Incentive Compensation Plan**                                               | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        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| **Disclosure of Compensation Related Costs, Share-based Payments [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            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| Incentive Compensation Plan                                                   | Incentive Compensation PlanOn January 20, 2009, the Board of Directors of the Company adopted with shareholder approval, the First Commonwealth Financial Corporation Incentive Compensation Plan. This plan allows for shares of common stock to be issued to employees, directors, and consultants of the Company and its subsidiaries as an incentive to aid in the financial success of the Company. The shares can be issued as options, stock appreciation rights, performance share or unit awards, dividend or dividend equivalent rights, stock awards, restricted stock awards, or other annual incentive awards. Up to 5,000,000 shares of stock can be awarded under this plan, of which, 4,330,038 shares are still eligible for awards.Restricted StockThe following provides detail on the restricted stock awards which were issued and outstanding in 2013, 2012 and 2011 in order to retain and attract key employees. The grant date fair value of the restricted stock awards is equal to the price of the Corporation’s common stock on grant date.Grant DateShares issuedGrant PriceVesting DateNumber of Equal Vesting Periods     August 16, 20133,000$7.57August 16, 20161May 31, 201345,0007.21May 31, 20163March 1, 201310,0007.35March 1, 20161February 24, 201234,0005.96December 31, 20141February 24, 201290,0005.96February 24, 20151January 1, 2012100,0005.26January 1, 20164November 21, 201110,0004.41November 21, 20141April 1, 201125,0006.82April 1, 20161January 22, 201030,1205.70January 22, 20122April 1, 200812,65412.35April 1, 20113November 12, 200735,00010.95November 12, 20103Compensation expense related to restricted stock was $509 thousand, $395 thousand and $249 thousand in 2013, 2012 and 2011, respectively. As of December 31, 2013, there was $2.2 million of unrecognized compensation cost related to unvested restricted stock awards granted.A summary of the status of First Commonwealth’s estimated unvested service-based restricted stock awards as of December 31 and changes for the years ended on those dates is presented below: 2013 2012 2011 Shares WeightedAverageGrant DateFair Value Shares WeightedAverageGrant DateFair Value Shares WeightedAverageGrant DateFair ValueOutstanding, beginning of the year253,000 $5.71 50,060 $6.00 34,338 $6.52Granted58,000 7.25 224,000 5.65 35,000 6.13Vested(35,000) 5.46 (17,060) 5.73 (19,278) 7.16Forfeited(5,000) 5.96 (4,000) 5.96 — —Outstanding, end of the year271,000 6.07 253,000 5.71 50,060 6.00The following provides detail on restricted stock awards estimated to be granted on a performance award basis during 2013, 2012 and 2011.  These plans were previously approved by the Board of Directors.Grant DateTarget Share AwardPerformance Period (years)Award if threshold metAward if targets are metAward if targets exceededAward if threshold not achievedVesting After Performance Period (years)Final vestingJanuary 17, 201154,166340%100%200%—%1January 17, 2014February 24, 201268,000340%100%200%—%1December 31, 2015January 28, 2013128,611340%100%200%—%1December 31, 2016The following table summarizes the estimated unvested target share awards for the Plans as of December 31: 2013 2012 2011Outstanding, beginning of the year151,333 93,333 —Granted138,611 74,000 126,000Vested— — —Forfeited(39,167) (16,000) (32,667)Outstanding, end of the year250,777 151,333 93,333The estimated unvested target awards for the Plans have an estimated fair value of $8.82 per share for each year based on the closing price of Company stock as of December 31, 2013.Stock Option PlanFirst Commonwealth’s stock based compensation plan expired on October 15, 2005, and is described below. All of the exercise prices and related number of shares have been adjusted to reflect historical stock splits. The plan permitted the Executive Compensation Committee to grant options for up to 4.5 million shares of First Commonwealth’s common stock through October 15, 2005.The vesting requirements and terms of options granted were at the discretion of the Executive Compensation Committee. Options granted in 2005 vested in the year granted. All options expire ten years from the grant date. All equity compensation plans were approved by security holders.A summary of the status of First Commonwealth’s outstanding stock options as of December 31 and changes for the years ended on those dates is presented below: 12/31/2013 12/31/2012 12/31/2011 Shares WeightedAverageExercisePrice Shares WeightedAverageExercisePrice Shares WeightedAverageExercisePriceOutstanding, beginning of the year196,322 $11.64 496,863 $10.03 640,866 $10.05Granted— — — — — —Exercised— — (130,672) 6.76 (13,760) 5.29Forfeited(169,322) 11.19 (169,869) 10.68 (130,243) 10.61Balance, end of the year27,000 14.49 196,322 11.64 496,863 10.03Exercisable at the end of the year27,000 14.49 196,322 11.64 496,863 10.03The intrinsic value of stock options exercised during the years ended December 31, 2012 and 2011 was $1.41 and $1.17 per share. There were no options exercised during the year ended December 31, 2013.The following table summarizes information about the stock options outstanding at December 31, 2013: Options Outstanding Options ExercisableRange of Exercise PricesNumberOutstanding WeightedAverageRemainingContractLife WeightedAverageExercisePrice NumberExercisable WeightedAverageExercisePrice$14.41 - $14.5527,000 0.6 $14.49 27,000 $14.49 |

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| - Definition
The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 50 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6406099&loc=d3e25284-112666Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64, 65, A240 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 40 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5444-113901Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 93-6 -Paragraph 53 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
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