| **Goodwill**                       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
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| **Goodwill Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Goodwill                           | GOODWILLThe carrying amount of goodwill at December 31, 2012 and 2011 was $141,375,000 and $141,357,000, respectively.  No impairment loss was recorded in 2012 or 2011.  The Corporation tested goodwill for impairment during 2011 and 2012.  In both valuations, the fair value exceeded the Corporation’s carrying value; therefore, it was concluded goodwill is not impaired. For additional details related to impairment testing, see the “GOODWILL” section of Management’s Discussion and Analysis of Financial Condition and Results of Operations included as Item 7 of this Annual Report on Form 10-K.In July 2012, FMIG acquired a book of business that resulted in goodwill acquired of $18,000.  This transaction was deemed to be an immaterial transaction. |

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| - Definition
The entire disclosure for goodwill.
+ References
No definition available.
+ Details**Name:**us-gaap_GoodwillDisclosureTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |