| **Goodwill**                       | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
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| **Goodwill Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Goodwill                           | GoodwillFASB ASC Topic 350-20, “Intangibles – Goodwill and Other” requires an annual valuation of the fair value of a reporting unit that has goodwill and a comparison of the fair value to the book value of equity to determine whether the goodwill has been impaired. Goodwill is also required to be tested on an interim basis if an event or circumstance indicates that it is more likely than not that an impairment loss has been incurred. When triggering events or circumstances indicate goodwill testing is required, an assessment of qualitative factors can be completed before performing the two step goodwill impairment test. ASU 2011-8 provides that if an assessment of qualitative factors determines it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, then the two step goodwill impairment test is not required.First Commonwealth is considered to be one reporting unit. The carrying amount of goodwill as of June 30, 2014 and December 31, 2013 was $159.4 million and $159.9 million, respectively. No impairment charges on goodwill or other intangible assets were incurred in 2014 or 2013. The $0.5 million decline in goodwill during the six months ended June 30, 2014 represents the amount of goodwill included in the carrying value of the investment advisory business which was sold during the first quarter of 2014.We test goodwill for impairment as of November 30th each year and again at any quarter-end if any material events occur during a quarter that may affect goodwill. An assessment of qualitative factors was completed as of June 30, 2014 and indicated that it is more likely than not that the fair value of First Commonwealth exceeds its carrying amount, therefore the two step goodwill impairment test was not considered necessary. The assessment of qualitative factors incorporated the results of the Step 1 goodwill impairment test completed as of November 30, 2013 as well as macroeconomic factors, industry and market considerations, the company’s overall financial performance, and other company specific events occurring since the completion of the November 30, 2013 test. As of June 30, 2014, goodwill was not considered impaired; however, changing economic conditions that may adversely affect our performance, fair value of our assets and liabilities, or stock price could result in impairment, which could adversely affect earnings in future periods. Management will continue to monitor events that could impact this conclusion in the future. |

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| - Definition
The entire disclosure for goodwill.
+ References
No definition available.
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