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| **Subsequent Events [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                     |
| Subsequent Events [Text Block]   | Subsequent EventsOn October 1, 2015,  First Commonwealth Bank, the banking subsidiary of First Commonwealth Financial Corporation, completed its acquisition of Columbus, Ohio based First Community Bank in an all-cash deal valued at $14.8 million. First Community Bank has assets of $102.8 million and four branch locations which will operate under the First Commonwealth name. |

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| - Definition
The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.
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