Disclosures Regarding Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment securities available for sale
Available for sale securities fair value	$ 290,805	$ 260,992
Investment securities available for sale
Available for sale securities fair value	290,805	260,992
State and municipal [Member]
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Collateralized mortgage obligations [Member]
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Other mortgage-backed (federal agencies) [Member]
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Recurring [Member]
Investment securities available for sale
Derivative financial instruments	820	481
Total assets measured at fair value on a recurring basis	291,625	261,473
Investment securities available for sale
Derivative financial instruments	820	481
Total assets measured at fair value on a recurring basis	291,625	261,473
Liabilities
Derivative financial instruments	278	25
Recurring [Member] \| State and municipal [Member]
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Recurring [Member] \| Collateralized mortgage obligations [Member]
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Recurring [Member] \| Other mortgage-backed (federal agencies) [Member]
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Recurring [Member] \| SBA loan-backed (federal agency) [Member]
Investment securities available for sale
Available for sale securities fair value	62,795
Investment securities available for sale
Available for sale securities fair value	62,795
Recurring [Member] \| Level 1 [Member]
Investment securities available for sale
Total assets measured at fair value on a recurring basis	40,901
Investment securities available for sale
Total assets measured at fair value on a recurring basis	40,901
Recurring [Member] \| Level 1 [Member] \| SBA loan-backed (federal agency) [Member]
Investment securities available for sale
Available for sale securities fair value	40,901
Investment securities available for sale
Available for sale securities fair value	40,901
Recurring [Member] \| Level 2 [Member]
Investment securities available for sale
Derivative financial instruments	820	481
Total assets measured at fair value on a recurring basis	250,724	261,473
Investment securities available for sale
Derivative financial instruments	820	481
Total assets measured at fair value on a recurring basis	250,724	261,473
Liabilities
Derivative financial instruments	278	25
Recurring [Member] \| Level 2 [Member] \| State and municipal [Member]
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Investment securities available for sale
Available for sale securities fair value	12,412	120,965
Recurring [Member] \| Level 2 [Member] \| Collateralized mortgage obligations [Member]
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Investment securities available for sale
Available for sale securities fair value	128,727	118,949
Recurring [Member] \| Level 2 [Member] \| Other mortgage-backed (federal agencies) [Member]
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Investment securities available for sale
Available for sale securities fair value	86,871	21,078
Recurring [Member] \| Level 2 [Member] \| SBA loan-backed (federal agency) [Member]
Investment securities available for sale
Available for sale securities fair value	21,894
Investment securities available for sale
Available for sale securities fair value	$ 21,894

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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