| **Income Taxes**                     | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| **Income Tax Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            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| Income Taxes                         | Income TaxesThe income tax provision (benefit) for the years ended December 31 is as follows: 2013 2012 2011 (dollars in thousands)Current tax provision for income exclusive of securities transactions:     Federal$2,509 $12,035 $651State68 72 161Total current tax provision2,577 12,107 812Deferred tax provision (benefit)12,704 2,551 (1,192)Total tax provision (benefit)$15,281 $14,658 $(380)The statutory to effective tax rate reconciliation for the years ended December 31 is as follows: 2013 2012 2011 Amount % ofPretaxIncome Amount % ofPretaxIncome Amount % ofPretaxIncome (dollars in thousands)Tax at statutory rate$19,867 35 % $19,814 35 % $5,213 35 %Increase (decrease) resulting from:           Income from bank owned life insurance(1,939) (3) (2,048) (4) (1,959) (13)Tax-exempt interest income, net(2,600) (5) (2,789) (5) (3,453) (23)Tax credits(144) — (267) — (270) (2)Other97 — (52) — 89 —Total tax provision (benefit)$15,281 27 % $14,658 26 % $(380) (3)%The total tax provision for financial reporting differs from the amount computed by applying the statutory federal income tax rate to income before taxes. First Commonwealth ordinarily generates an annual effective tax rate that is less than the statutory rate of 35% due to benefits resulting from tax-exempt interest, income from bank owned life insurance and tax benefits associated with low income housing tax credits. The consistent level of tax benefits that reduce First Commonwealth’s tax rate below the 35% statutory rate produced an annual effective tax rate of 27% and 26% for the years ended December 31, 2013 and 2012, respectively.  The relatively low level of annual pretax income produced a tax benefit for the year ended December 31, 2011.The tax effects of temporary differences between the financial statement carrying amounts and the tax bases of assets and liabilities that represent significant portions of the deferred tax assets and liabilities at December 31 are presented below:  2013 2012 (dollars in thousands)Deferred tax assets:   Allowance for credit losses$18,979 $23,515Postretirement benefits other than pensions726 769Alternative minimum tax credit carryforward13,896 13,026Unrealized loss on securities available for sale11,235 —Writedown of other real estate owned207 3,647Deferred compensation2,118 2,203Accrued interest on nonaccrual loans1,481 3,887Other-than-temporary impairment of securities9,693 15,233Depreciation of assets1,546 952Accrued incentives1,153 —Unfunded loan commitment allowance1,106 836Deferred rent653 —Other2,462 2,795Total deferred tax assets65,255 66,863Deferred tax liabilities:   Basis difference in assets acquired(518) (808)Loan origination fees and costs(637) (606)Income from unconsolidated subsidiary(590) (575)Unrealized gain on securities available for sale— (592)Other(332) (150)Total deferred tax liabilities(2,077) (2,731)Net deferred tax asset$63,178 $64,132The net deferred tax asset of $63.2 million as of December 31, 2013 includes a $13.9 million alternative minimum tax credit carryforward with an indefinite life. There is also a $9.7 million deferred tax asset for other-than-temporary impairment of securities, of which $0.4 million are potential capital losses that can only be utilized if capital gains are realized.Management assesses all available positive and negative evidence to estimate if sufficient future taxable income will be generated to utilize the existing deferred tax assets. In evaluating deferred tax assets, future taxable income forecasted over the next three years was considered. The amount of future taxable income used in management’s valuation is based upon management approved forecasts, evaluation of historical earnings levels, proven ability to raise capital to support growth or during times of economic stress and consideration of prudent and feasible potential tax strategies. If future events differ from our current forecasts, a valuation allowance may be required, which could have a material impact on our financial condition and results of operations. Based on our evaluation, including the consideration of the weighting of positive and negative evidence, as of December 31, 2013, management has determined that no valuation allowance is necessary for the deferred tax assets because it is more likely than not that these assets will be realized through future reversals of existing temporary differences and through future taxable income.First Commonwealth adopted new authoritative accounting guidance issued under FASB ASC Topic 740-10, “Accounting for Uncertainty in Income Taxes” as of January 1, 2007, and had no material unrecognized tax benefits or accrued interest and penalties as of December 31, 2013. We do not expect the total amount of unrecognized tax benefits to significantly increase in the next twelve months and will record interest and penalties as a component of noninterest expense.First Commonwealth is subject to routine audits of our tax returns by the Internal Revenue Service as well as all states in which we conduct business. Federal and state income tax years 2010 through 2012 are open for examination as of December 31, 2013. |

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| - Definition
The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 136, 172 -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 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43, 44, 45, 46, 47, 48, 49 -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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