| **Investment Securities (Tables)**                                                 | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
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| **Investments Securities [Abstract]**                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Schedule of Available For Sale, Held-to-Maturity, and Restricted Equity Securities | The following tables summarize the amortized cost and estimated fair value of investment securities at December 31, 2012 and 2011:  Amortized  Unrealized  Unrealized  Fair Value  As of December 31, 2012 Cost  Gains  Losses  (Estimated) Securities available for sale        Mortgage-backed securities $164,752,000  $4,636,000  $(295,000) $169,093,000 State and political subdivisions  113,069,000   8,074,000   (199,000)  120,944,000 Corporate securities  -   -   -   - Other equity securities  1,578,000   43,000   (44,000)  1,577,000   $279,399,000  $12,753,000  $(538,000) $291,614,000 Securities to be held to maturity                U.S. Government-sponsored agencies $60,919,000  $242,000  $(182,000) $60,979,000 Mortgage-backed securities  39,193,000   2,850,000   (19,000)  42,024,000 State and political subdivisions  42,908,000   4,036,000   -   46,944,000 Corporate securities  300,000   -   -   300,000   $143,320,000  $7,128,000  $(201,000) $150,247,000 Restricted equity securities                Federal Home Loan Bank Stock $13,412,000  $-  $-  $13,412,000 Federal Reserve Bank Stock  1,036,000   -   -   1,036,000   $14,448,000  $-  $-  $14,448,000   Amortized  Unrealized  Unrealized  Fair Value  As of December 31, 2011 Cost  Gains  Losses  (Estimated) Securities available for sale        Mortgage-backed securities $191,924,000  $6,486,000  $(178,000) $198,232,000 State and political subdivisions  80,259,000   5,484,000   (17,000)  85,726,000 Corporate securities  1,098,000   -   (287,000)  811,000 Other equity securities  1,535,000   37,000   (139,000)  1,433,000   $274,816,000  $12,007,000  $(621,000) $286,202,000 Securities to be held to maturity                U.S. Government-sponsored agencies $19,390,000  $132,000  $-  $19,522,000 Mortgage-backed securities  56,800,000   3,900,000   (3,000)  60,697,000 State and political subdivisions  46,171,000   4,159,000   (172,000)  50,158,000 Corporate securities  300,000   -   -   300,000   $122,661,000  $8,191,000  $(175,000) $130,677,000 Restricted equity securities                Federal Home Loan Bank Stock $14,031,000  $-  $-  $14,031,000 Federal Reserve Bank Stock  1,412,000   -   -   1,412,000   $15,443,000  $-  $-  $15,443,000  |
| Contractual Maturities of Investment Securities                                    | The following table summarizes the contractual maturities of investment securities at December 31, 2012:  Securities available for sale  Securities to be held to maturity   Amortized Cost  Fair Value (Estimated)  Amortized Cost  Fair Value (Estimated) Due in 1 year or less $18,761,000  $18,926,000  $3,754,000  $3,785,000 Due in 1 to 5 years  27,243,000   27,816,000   11,950,000   12,701,000 Due in 5 to 10 years  16,686,000   17,666,000   27,461,000   29,986,000 Due after 10 years  215,131,000   225,629,000   100,155,000   103,775,000 Equity securities  1,578,000   1,577,000   -   -   $279,399,000  $291,614,000  $143,320,000  $150,247,000 The following table summarizes the contractual maturities of investment securities at December 31, 2011:  Securities available for sale  Securities to be held to maturity In thousands of dollars AmortizedCost  Fair Value (Estimated)  AmortizedCost  Fair Value (Estimated) Due in 1 year or less $6,617,000  $6,773,000  $5,179,000  $5,227,000 Due in 1 to 5 years  18,792,000   19,473,000   10,085,000   10,654,000 Due in 5 to 10 years  23,219,000   24,065,000   23,027,000   24,694,000 Due after 10 years  224,653,000   234,458,000   84,370,000   90,102,000 Equity securities  1,535,000   1,433,000   -   -   $274,816,000  $286,202,000  $122,661,000  $130,677,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| Schedule of Securities Gains and Losses                                            | The following table shows securities gains and losses for 2012, 2011 and 2010:  2012  2011  2010 Proceeds from sales of securities $26,437,000  $140,417,000  $202,000 Gross realized gains  2,257,000   4,020,000   2,000 Gross realized losses  (289,000)  (727,000)  - Net gain $1,968,000  $3,293,000  $2,000 Related income taxes $689,000  $1,153,000  $1,000 The following table summarizes activity in the unrealized gain or loss on available for sale securities included in other comprehensive income for the years ended December 31, 2012, 2011 and 2010.Years ended December 31, 2012  2011  2010 Balance at beginning of year $7,401,000  $(2,057,000) $(125,000)Unrealized gains (losses) arising during the period  2,797,000   17,844,000   (2,971,000)Realized gains during the period  (1,968,000)  (3,293,000)  (2,000)Related deferred taxes  (290,000)  (5,093,000)  1,041,000 Net change  539,000   9,458,000   (1,932,000)Balance at end of year $7,940,000  $7,401,000  $(2,057,000)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Schedule of Temporary Impairment Losses                                            |       Information regarding securities temporarily impaired as of December 31, 2012 is summarized below:  Less than 12 months  12 months or more  Total   Fair  Unrealized  Fair  Unrealized  Fair  Unrealized  As of December 31, 2012 Value  Losses  Value  Losses  Value  Losses U.S. Government-sponsored agencies $15,817,000  $(182,000) $-  $-  $15,817,000  $(182,000)Mortgage-backed securities  9,982,000   (231,000)  2,534,000   (83,000)  12,516,000   (314,000)State and political subdivisions  8,621,000   (199,000)  -   -   8,621,000   (199,000)Corporate securities  -   -   -   -   -   - Other equity securities  -   -   222,000   (44,000)  222,000   (44,000)  $34,420,000  $(612,000) $2,756,000  $(127,000) $37,176,000  $(739,000)Information regarding securities temporarily impaired as of December 31, 2011 is summarized below:  Less than 12 months  12 months or more  Total   Fair  Unrealized  Fair  Unrealized  Fair  Unrealized  As of December 31, 2011 Value  Losses  Value  Losses  Value  Losses U.S. Government-sponsored agencies $-  $-  $-  $-  $-  $- Mortgage-backed securities  12,489,000   (25,000)  6,780,000   (156,000)  19,269,000   (181,000)State and political subdivisions  1,984,000   (17,000)  1,667,000   (172,000)  3,651,000   (189,000)Corporate securities  -   -   811,000   (287,000)  811,000   (287,000)Other equity securities  154,000   (120,000)  34,000   (19,000)  188,000   (139,000)  $14,627,000  $(162,000) $9,292,000  $(634,000) $23,919,000  $(796,000)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |

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| - Definition
Tabular presentation of available for sale securities, held-to-maturity securities and restricted equity securities as of the balance sheet date.
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Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.
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| - Definition
Tabular disclosure of the proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been included in earnings as a result of those sales.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Topic 320 -SubTopic 10 -Publisher FASB -Number  -Article  -Subparagraph (a) -Name Accounting Standards Codification -Paragraph 9 -Section 50 -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563
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| - Definition
Tabular disclosure of investments in an unrealized loss position for which other-than-temporary impairments have not been recognized in earnings (including investments for which a portion of an other-than-temporary impairment has been recognized in other comprehensive income), including: (a) the aggregate related fair value of investments with unrealized losses, (b) the aggregate amount of unrealized losses (that is, the amount by which amortized cost basis exceeds fair value).
+ References
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