Fair Values of Financial Instruments - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Investment securities available for sale	$ 696,862	$ 658,400
Investment securities held to maturity	611,933	632,380
Loans held for sale	2,929	9,894
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	127,927	102,170
Interest-bearing time deposits	24,459	32,315
Investment securities available for sale	18,765
Liabilities:
Deposits	4,427,605	4,095,004
Significant Other Observable Inputs (Level 2)
Assets:
Investment securities available for sale	672,928	652,468
Investment securities held to maturity	597,246	598,082
Loans held for sale	2,929	9,894
Federal Reserve and Federal Home Loan Bank stock	17,964	37,633
Interest rate swap asset	6,310	4,974
Interest receivable	26,194	24,415
Liabilities:
Deposits	1,111,491	1,177,142
Borrowings:
Federal funds purchased	120,349	49,721
Securities sold under repurchase agreements	146,449	155,325
Federal Home Loan Bank advances	297,465	236,375
Subordinated debentures and term loans	105,930	103,643
Interest rate swap liability	8,477	8,070
Interest payable	3,110	3,092
Significant Unobservable Inputs (Level 3)
Assets:
Investment securities available for sale	5,169	5,932
Investment securities held to maturity	14,687	34,298
Loans	4,933,552	4,539,940
Carrying Amount
Assets:
Cash and cash equivalents	127,927	102,170
Interest-bearing time deposits	24,459	32,315
Investment securities available for sale	696,862	658,400
Investment securities held to maturity	607,643	618,599
Loans held for sale	2,929	9,894
Loans	5,073,608	4,631,369
Federal Reserve and Federal Home Loan Bank stock	17,964	37,633
Interest rate swap asset	6,310	4,974
Interest receivable	26,194	24,415
Liabilities:
Deposits	5,556,498	5,289,647
Borrowings:
Federal funds purchased	120,349	49,721
Securities sold under repurchase agreements	146,480	155,325
Federal Home Loan Bank advances	298,923	235,652
Subordinated debentures and term loans	128,445	127,846
Interest rate swap liability	8,477	8,070
Interest payable	$ 3,110	$ 3,092

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

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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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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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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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The face amount of loans that will be sold to other entities.

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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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