| **Investment Securities**                              | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| **Investments, Debt and Equity Securities [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| Investment Securities                                  | INVESTMENT SECURITIES The amortized cost, gross unrealized gains, gross unrealized losses and approximate fair values of the investment securities at the dates indicated were:  AmortizedCostGross Unrealized GainsGross Unrealized LossesFairValueAvailable for sale at September 30, 2013    U.S. Government-sponsored agency securities$3,791$18$9$3,800State and municipal200,6624,9833,463202,182U.S. Government-sponsored mortgage-backed securities397,6876,1365,654398,169Corporate obligations6,335 5,851484Equity securities1,706  1,706Total available for sale610,18111,13714,977606,341Held to maturity at September 30, 2013    State and municipal115,7964986116,288U.S. Government-sponsored mortgage-backed securities191,9986,600503198,095Total held to maturity307,7947,098509314,383Total Investment Securities$917,975$18,235$15,486$920,724  AmortizedCostGross Unrealized GainsGross Unrealized LossesFairValueAvailable for sale at December 31, 2012    U.S. Government-sponsored agency securities$4,475$165 $4,640State and municipal148,18710,025$18158,194U.S. Government-sponsored mortgage-backed securities337,63110,99446348,579Corporate obligations6,105 5,881224Equity securities1,706  1,706Total available for sale498,10421,1845,945513,343Held to maturity at December 31, 2012    State and municipal117,2275,4891122,715U.S. Government-sponsored mortgage-backed securities243,79311,68115255,459Total held to maturity361,02017,17016378,174Total Investment Securities$859,124$38,354$5,961$891,517The amortized cost and fair value of available for sale securities and held to maturity securities at September 30, 2013, by contractual maturity, are shown below.  Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.  Available for SaleHeld to Maturity AmortizedCostFairValueAmortizedCostFairValueMaturity Distribution at September 30, 2013:    Due in one year or less$8,404$8,591$1,060$1,061Due after one through five years11,97212,48113,11613,324Due after five through ten years57,70859,11059,47359,634Due after ten years132,704126,28442,14742,269 $210,788$206,466$115,796$116,288U.S. Government-sponsored mortgage-backed securities397,687398,169191,998198,095Equity securities1,7061,706Total Investment Securities$610,181$606,341$307,794$314,383The carrying value of securities pledged as collateral, to secure public deposits and for other purposes, was $375,411,000 at September 30, 2013, and $335,775,000 at December 31, 2012.The book value of securities sold under agreements to repurchase amounted to $111,138,000 at September 30, 2013, and $128,094,000 at December 31, 2012.Gross gains and losses on the sales and redemptions of available for sale securities, and other-than-temporary impairment (“OTTI”) losses recognized for the three and nine months ended September 30, 2013 and 2012 are shown below. Three Months EndedSeptember 30,Nine Months EndedSeptember 30, 2013201220132012Sales and Redemptions of Available for Sale Securities:    Gross gains$—$843$487$2,134Gross losses————Other-than-temporary impairment losses———$—  The following table shows the Corporation’s investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at September 30, 2013, and December 31, 2012:  Less than12 Months12 Months or LongerTotal FairValueGrossUnrealizedLossesFairValueGrossUnrealizedLossesFairValueGrossUnrealizedLossesTemporarily Impaired Investment      Securities at September 30, 2013      U.S. Government-sponsored agency securities$1,439 $9     $1,439 $9State and municipal76,6813,467$239$276,9203,469U.S. Government-sponsored mortgage-backed securities204,7436,157  204,7436,157Corporate obligations  4535,8514535,851Total Temporarily Impaired Investment Securities$282,863$9,633$692$5,853$283,555$15,486   Less than12 Months12 Months or LongerTotal FairValueGrossUnrealized LossesFairValueGrossUnrealized LossesFairValueGrossUnrealized LossesTemporarily Impaired Investment      Securities at December 31, 2012      State and municipal$4,524$19  $4,524$19U.S. Government-sponsored mortgage-backed securities12,32061  12,32061Corporate obligations  $194$5,8811945,881Total Temporarily Impaired Investment Securities$16,844$80$194$5,881$17,038$5,961Certain investments in debt and equity securities are reported in the financial statements at an amount less than their historical cost as indicated in the table below.September 30, 2013December 31, 2012Investments reported at less than historical cost:  Historical cost$299,041$22,999Fair value$283,555$17,038Percent of the Corporation's available for sale and held to maturity portfolio31.0%1.9% The Corporation’s management has evaluated all securities with unrealized losses for other-than-temporary impairment ("OTTI") as of September 30, 2013.  The evaluations are based on the nature of the securities, the extent and duration of the loss and the intent and ability of the Corporation to hold these securities either to maturity or through the expected recovery period.The current unrealized losses are primarily concentrated within trust preferred securities held by the Corporation.  Such investments have an amortized cost of $6.3 million and a fair value of $453,000, which is less than 1 percent of the Corporation’s entire investment portfolio.  On all but one small pool investment, the Corporation utilized Moody’s to determine their fair value.In determining the fair value of the trust preferred securities, the Corporation utilizes a third party for portfolio accounting services, including market value input.  The Corporation has obtained an understanding of what inputs are being used by the vendor in pricing the portfolio and how the vendor was classifying these securities based upon these inputs.  From these discussions, the Corporation’s management is comfortable that the classifications are proper.  The Corporation has gained trust in the data for two reasons:  (a) independent spot testing of the data is conducted by the Corporation through obtaining market quotes from various brokers on a periodic basis and (b) actual gains or loss resulting from the sale of certain securities has proven the data to be accurate over time.  Discount rates used in the OTTI cash flow analysis on these variable rate securities were those margins in effect at the inception of the security added to the appropriate three-month LIBOR spot rate obtained from the forward LIBOR curve used to project future principal and interest payments.  These spreads ranged from .85 percent to 1.57 percent spread over LIBOR.Management believes the declines in fair value for these securities are temporary.  Should any additional impairment of any of these securities become other than temporary, the cost basis of the investment will be reduced and the resulting loss recognized in net income in the period the OTTI is identified.U.S. Government-Sponsored Mortgage-Backed SecuritiesThe unrealized losses on the Corporation’s investment in U.S. Government-sponsored mortgage-backed securities were a result of changes in interest rates.  The Corporation expects to recover the amortized cost basis over the term of the securities as the decline in market value is attributable to changes in interest rates and not credit quality.  The Corporation does not intend to sell the investment and it is not more likely than not that the Corporation will be required to sell the investment before recovery of its new, lower amortized cost basis, which may be maturity.  The Corporation does not consider the investment securities to be other-than-temporarily impaired at September 30, 2013.State and MunicipalThe unrealized losses on the Corporation’s investments in securities of state and political subdivisions were caused by changes in interest rates.  The contractual terms of those investments do not permit the issuer to settle the securities at a price less than the amortized cost basis of the investments.  The Corporation does not intend to sell the investment and it is not more likely than not that the Corporation will be required to sell the investment before recovery of its new, lower amortized cost basis, which may be maturity.  The Corporation does not consider the investment securities to be other-than-temporarily impaired at September 30, 2013.Corporate ObligationsThe Corporation’s unrealized losses on Corporate Obligations were due to the decline in value related to the pooled trust preferred securities, and is attributable to temporary illiquidity and the financial crisis affecting these markets, coupled with the potential credit loss resulting from the adverse change in expected cash flows.  Due to the illiquidity in the market, it is unlikely that the Corporation would be able to recover its investment in these securities if the Corporation sold the securities at this time.  Management has analyzed the cash flow characteristics of the securities and this analysis included utilizing the most recent trustee reports and any other relevant market information, including announcements of deferrals or defaults of trust preferred securities.  The Corporation compared expected discounted cash flows, based on performance indicators of the underlying assets in the security, to the carrying value of the investment to determine if OTTI existed.  The Corporation does not intend to sell the investment, and it is not more likely than not that the Corporation will be required to sell the investment before recovery of its new, lower amortized cost basis, which may be maturity.  The Corporation does not consider the remainder of the investment securities, which are classified as Level 3 inputs in the fair value hierarchy, to be other-than-temporarily impaired at September 30, 2013.  Credit Losses Recognized on InvestmentsCertain debt securities have experienced fair value deterioration due to credit losses and other market factors.  The following table provides information about debt securities for which only a credit loss was recognized in income and other losses were recorded in other comprehensive income.  AccumulatedCredit Losses in2013AccumulatedCredit Losses in2012Credit losses on debt securities held:  Balance, January 1$11,355$11,355Additions related to other-than-temporary losses not previously recognizedBalance, September 30$11,355$11,355 |

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| - Definition
The entire disclosure for  investments in certain debt and equity securities.
+ References
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