| **Premises and Equipment**                   | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
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| **Property, Plant and Equipment [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Premises and Equipment                       | PREMISES AND EQUIPMENTThe following table summarizes the Corporation's premises and equipment as of December 31, 2012 and 2011: 2012 2011Cost at December 31:   Land$14,692 $14,296Buildings and Leasehold Improvements62,606 62,317Equipment42,564 39,789Total Cost119,862 116,402Accumulated Depreciation and Amortization(67,113) (65,389)Net$52,749 $51,013  The Corporation is committed under various non-cancelable lease contracts for certain subsidiary office facilities and equipment. Total lease expense for 2012, 2011 and 2010 was $2,812,000, $2,636,000 and  $2,801,000, respectively. The future minimum rental commitments required under the operating leases in effect at December 31, 2012, expiring at various dates through the year 2027 are as follows for the years ending December 31: Future Minimum Rental Commitments2013$2,28420142,02520151,85220161,4412017865After 20171,428Total Future Minimum Obligations$9,895 |

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| - Definition
The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13-14) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 5 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230
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