Consolidated Condensed Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Securities available-for-sale, amortized cost	$ 1,251,451	$ 1,299,980
Securities held-to-maturity, fair value	$ 136,418	$ 143,490
Preferred Stock, Shares Authorized	200,000us-gaap_PreferredStockSharesAuthorized	200,000us-gaap_PreferredStockSharesAuthorized
Preferred Stock, Shares Issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock no par value	$ 0us-gaap_CommonStockNoParValue	$ 0us-gaap_CommonStockNoParValue
Common stock shares authorized	20,000,000us-gaap_CommonStockSharesAuthorized	20,000,000us-gaap_CommonStockSharesAuthorized
Common stock shares issued	16,150,876us-gaap_CommonStockSharesIssued	16,150,888us-gaap_CommonStockSharesIssued
Treasury stock shares	779,989us-gaap_TreasuryStockShares	758,489us-gaap_TreasuryStockShares

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Face amount per share of no-par value common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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