Unobservable Inputs Used in Recurring and Nonrecurring Level 3 Fair Value Measurements Other Than Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Discounted Cash Flow \| State and municipal \| Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Maturity/Call date	1 month
Blend of US Muni BQ curve	A-
Discount rate	1.00%
Discounted Cash Flow \| State and municipal \| Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Maturity/Call date	11 years
Blend of US Muni BQ curve	BBB-
Discount rate	4.00%
Discounted Cash Flow \| Corporate obligations
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate Description	3 month LIBOR
Discount to reflect current market conditions	2.00%
Collateral Based Measurements \| Impaired Loans \| Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	0.00%
Collateral Based Measurements \| Impaired Loans \| Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions and ultimate collectability	50.00%
Appraisals \| Other Real Estate Owned \| Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions	0.00%
Appraisals \| Other Real Estate Owned \| Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount to reflect current market conditions	20.00%
Significant Unobservable Inputs (Level 3) \| Discounted Cash Flow \| State and municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available for sale securities	17,307
Significant Unobservable Inputs (Level 3) \| Discounted Cash Flow \| Corporate obligations
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	371
Significant Unobservable Inputs (Level 3) \| Collateral Based Measurements \| Impaired Loans
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	11,096
Significant Unobservable Inputs (Level 3) \| Appraisals \| Other Real Estate Owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value	4,411

- Definition

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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