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Subordinated Debentures - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011
First Commonwealth Capital Trust [Member] |  |
Subordinated Borrowing [Line Items] |  |
Percentage of common equity owned by First Commonwealth | 100.00% |
First Commonwealth Capital Trust III [Member] |  |
Subordinated Borrowing [Line Items] |  |
Floating rate | LIBOR + 2.85 | LIBOR + 2.85
Deferred issuance costs | $ 630 |
Redemption price as percentage of principal amount | 100.00% |
First Commonwealth Capital Trust II [Member] |  |
Subordinated Borrowing [Line Items] |  |
Floating rate | LIBOR + 2.85 | LIBOR + 2.85
Deferred issuance costs | 471 |
Redemption price as percentage of principal amount | 100.00% |
First Commonwealth Capital Trust I [Member] |  |
Subordinated Borrowing [Line Items] |  |
Deferred issuance costs | $ 996 |
Redemption price as percentage of principal amount | 103.325% |
Fixed Interest Rate | 9.50% | 9.50%
Debentures authorized for redemption percentage | 100.00% |

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- Definition Percentage of outstanding principal available to be redeemed. + References No definition available. + Details
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- Definition Redemption Price As Percentage Of Principal Amount + References No definition available. + Details
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- Definition Subordinated Borrowing Variable Rate Description + References No definition available. + Details
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- Definition Stated interest rate of the subordinated debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Paragraph 80 -Subparagraph Exhibit 4-8, 9 -IssueDate 2006-05-01 -Chapter 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Paragraph 08 -IssueDate 2006-05-01 -Chapter 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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. + Details
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- Details
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- Definition Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
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