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.

+ References+ Details

Quantitative Information about Recurring Level Three Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified					1 Months Ended	9 Months Ended		9 Months Ended								9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Corporate Securities [Member]	Dec. 31, 2011 Corporate Securities [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Multi Family [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Corporate Securities [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Corporate Securities [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Corporate Securities [Member] Discounted Cash Flows Valuation Technique [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Multi Family [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Minimum [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Commercial [Member] Impaired Loans [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Nonresidential Real Estate [Member] Commercial Mortgage Loans, Non Owner Occupied [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Multi Family [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Residential Real Estate [Member] Residential Real Estate Other Financing Receivable [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Maximum [Member] Cost Sales Income Approach Valuation Technique [Member] Construction [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Significant Unobservable Inputs (Level 3) [Member] Corporate Securities [Member] Discounted Cash Flows Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investment securities available-for-sale	$ 302,544	$ 322,512	$ 1,060	$ 1,060										$ 1,060	$ 1,060														$ 1,060
Probability of default																0.00%
Impaired loans	$ 1,149,104	$ 1,112,788					$ 17,111	$ 875	$ 8,255	$ 9,645	$ 577	$ 2,417	$ 4,470
Unobservable Input, discounts ranging					5.00%	10.00%											5.00%	5.00%	5.00%	5.00%	5.00%	5.00%	10.00%	10.00%	10.00%	10.00%	10.00%	10.00%
Valuation Techniques								Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach	Cost, sales, income approach