Disclosures About Fair Value of Assets and Liabilities - Estimated Fair Values of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets:
Investment securities available for sale	$ 606,341	$ 513,343
Investment securities held to maturity - fair value	314,383	378,174
Carrying (Reported) Amount
Assets:
Cash and due from banks	92,341	101,460
Interest-bearing time deposits	18,875	38,443
Investment securities available for sale	606,341	513,343
Investment securities held to maturity - fair value	307,794	361,020
Mortgage loans held for sale	5,312	22,300
Loans	2,859,233	2,832,843
Federal Reserve Bank and Federal Home Loan Bank stock	32,790	32,785
Interest rate swap and cap asset	3,475	6,300
Interest receivable	16,171	16,367
Liabilities:
Deposits	3,255,846	3,346,383
Borrowings:
Federal funds purchased	115,938	18,862
Securities sold under repurchase agreements	123,935	141,828
Federal Home Loan Bank advances	172,292	94,238
Subordinated debentures, revolving credit lines and term loans	111,849	112,161
Interest rate swap liability	4,577	9,766
Interest payable	1,155	1,841
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and due from banks	92,341	101,460
Interest-bearing time deposits	18,875	38,443
Liabilities:
Deposits	2,548,183	2,478,706
Significant Other Observable Inputs (Level 2)
Assets:
Investment securities available for sale	585,343	495,015
Investment securities held to maturity - fair value	303,371	366,590
Mortgage loans held for sale	5,312	22,300
Federal Reserve Bank and Federal Home Loan Bank stock	32,790	32,785
Interest rate swap and cap asset	3,475	6,300
Interest receivable	16,171	16,367
Liabilities:
Deposits	700,168	865,793
Borrowings:
Federal funds purchased	115,938	18,862
Securities sold under repurchase agreements	124,195	142,318
Federal Home Loan Bank advances	173,449	97,357
Subordinated debentures, revolving credit lines and term loans	63,391	62,133
Interest rate swap liability	4,577	9,766
Interest payable	1,155	1,841
Significant Unobservable Inputs (Level 3)
Assets:
Investment securities available for sale	20,998	18,328
Investment securities held to maturity - fair value	11,012	11,584
Loans	$ 2,822,465	$ 2,852,614

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Federal Home Loan Bank Advances Fair Value

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Interest Bearing Deposits with Banks, Fair Value Disclosure

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Interest Payable Fair Value Disclosure

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Interest Rate Swap Liabilities Fair Value Disclosure

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Interest Rate Swaps Assets Fair Value Disclosure

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Interest Receivable, Fair Value Disclosure

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Name Accounting Standards Codification

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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-Glossary Cash

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-Glossary Cash Equivalents

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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-Name Accounting Standards Codification

-Topic 942

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Fair value of investments in debt securities classified as held-to-maturity.

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value portion of mortgage loans held-for-sale.

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Fair value portion of other liabilities.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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