| **Investment Securities (Tables)**                                                 | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
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| **Investments, Debt and Equity 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, 2013 and 2012: Amortized Unrealized Unrealized Fair ValueAs of December 31, 2013Cost Gains Losses (Estimated)Securities available for sale       Mortgage-backed securities$180,109,000 $1,392,000 $(3,772,000) $177,729,000State and political subdivisions134,188,000 1,458,000 (9,331,000) 126,315,000Other equity securities1,666,000 116,000 (2,000) 1,780,000 $315,963,000 $2,966,000 $(13,105,000) $305,824,000Securities to be held to maturity       U.S. Government-sponsored agencies$92,280,000 $1,000 $(12,757,000) $79,524,000Mortgage-backed securities35,712,000 1,440,000 (1,336,000) 35,816,000State and political subdivisions40,985,000 1,823,000 (112,000) 42,696,000Corporate securities300,000 — — 300,000 $169,277,000 $3,264,000 $(14,205,000) $158,336,000Restricted equity securities       Federal Home Loan Bank Stock$12,875,000 $— $— $12,875,000Federal Reserve Bank Stock1,037,000 — — 1,037,000 $13,912,000 $— $— $13,912,000 Amortized Unrealized Unrealized Fair ValueAs of December 31, 2012Cost Gains Losses (Estimated)Securities available for sale       Mortgage-backed securities$164,752,000 $4,636,000 $(295,000) $169,093,000State and political subdivisions113,069,000 8,074,000 (199,000) 120,944,000Other equity securities1,578,000 43,000 (44,000) 1,577,000 $279,399,000 $12,753,000 $(538,000) $291,614,000Securities to be held to maturity       U.S. Government-sponsored agencies$60,919,000 $242,000 $(182,000) $60,979,000Mortgage-backed securities39,193,000 2,850,000 (19,000) 42,024,000State and political subdivisions42,908,000 4,036,000 — 46,944,000Corporate securities300,000 — — 300,000 $143,320,000 $7,128,000 $(201,000) $150,247,000Restricted equity securities       Federal Home Loan Bank Stock$13,412,000 $— $— $13,412,000Federal Reserve Bank Stock1,036,000 — — 1,036,000 $14,448,000 $— $— $14,448,000 |
| Contractual Maturities of Investment Securities                                    | The following table summarizes the contractual maturities of investment securities at December 31, 2013: 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$717,000 $721,000 $268,000 $273,000Due in 1 to 5 years20,547,000 20,636,000 6,420,000 6,790,000Due in 5 to 10 years16,114,000 16,267,000 33,442,000 33,828,000Due after 10 years276,919,000 266,420,000 129,147,000 117,445,000Equity securities1,666,000 1,780,000 — — $315,963,000 $305,824,000 $169,277,000 $158,336,000The following table summarizes the contractual maturities of investment securities at December 31, 2012: Securities available for sale Securities to be held to maturityIn thousands of dollarsAmortized Cost Fair Value (Estimated) Amortized Cost Fair Value (Estimated)Due in 1 year or less$18,761,000 $18,926,000 $3,754,000 $3,785,000Due in 1 to 5 years27,243,000 27,816,000 11,950,000 12,701,000Due in 5 to 10 years16,686,000 17,666,000 27,461,000 29,986,000Due after 10 years215,131,000 225,629,000 100,155,000 103,775,000Equity securities1,578,000 1,577,000 — — $279,399,000 $291,614,000 $143,320,000 $150,247,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Schedule of Securities Gains and Losses                                            | The following table shows securities gains and losses for 2013, 2012 and 2011: 2013 2012 2011Proceeds from sales of securities$10,563,000 $26,437,000 $140,417,000Gross realized gains1,087,000 2,257,000 4,020,000Gross realized losses— (289,000) (727,000)Net gain$1,087,000 $1,968,000 $3,293,000Related income taxes$380,000 $689,000 $1,153,000                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Schedule of Temporary Impairment Losses                                            | Information regarding securities temporarily impaired as of December 31, 2013 is summarized below: Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair UnrealizedAs of December 31, 2013Value Losses Value Losses Value LossesU.S. Government-sponsored agencies$78,724,000 $(12,757,000) $— $— $78,724,000 $(12,757,000)Mortgage-backed securities96,263,000 (4,977,000) 5,451,000 (131,000) 101,714,000 (5,108,000)State and political subdivisions69,406,000 (7,895,000) 7,150,000 (1,548,000) 76,556,000 (9,443,000)Other equity securities— — 50,000 (2,000) 50,000 (2,000) $244,393,000 $(25,629,000) $12,651,000 $(1,681,000) $257,044,000 $(27,310,000)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 UnrealizedAs of December 31, 2012Value Losses Value Losses Value LossesU.S. Government-sponsored agencies$15,817,000 $(182,000) $— $— $15,817,000 $(182,000)Mortgage-backed securities9,982,000 (231,000) 2,534,000 (83,000) 12,516,000 (314,000)State and political subdivisions8,621,000 (199,000) — — 8,621,000 (199,000)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)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

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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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No definition available.
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| - Definition
Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.
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No definition available.
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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 -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=27724398&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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563
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