Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Fair value of financial assets and liabilities measured on recurring basis
Securities available for sale	$ 555,300		$ 554,405
Derivative assets	7,652		6,663
Derivative liabilities	5,648		5,136
Loans held for sale	16,612	12,126	11,258
Mortgage servicing intangibles	915
Level 1 Inputs [Member]
Fair value of financial assets and liabilities measured on recurring basis
Securities available for sale			35,096
Mortgage servicing intangibles
Level 2 Inputs [Member]
Fair value of financial assets and liabilities measured on recurring basis
Securities available for sale	544,813		506,811
Derivative assets	7,652		6,663
Derivative liabilities	5,648		5,136
Loans held for sale	16,612		11,258
Mortgage servicing intangibles
Level 3 Inputs [Member]
Fair value of financial assets and liabilities measured on recurring basis
Securities available for sale	10,487		12,498
Mortgage servicing intangibles	$ 915

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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