Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail)

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Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) (Non-recurring Basis [Member], USD $)
Jun. 30, 2013
Dec. 31, 2012
Commercial Property Loan [Member] | Other Real Estate Owned [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale $ 513,000  
Small Business Administration Loans Held for Sale [Member] | Other Real Estate Owned [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale 387,000  
Small Business Administration Loans Held for Sale [Member] | Non-Performing Loans Held for Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale   484,000
Real estate loans [Member] | Other Real Estate Owned [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale   774,000
Real estate loans [Member] | Non-Performing Loans Held for Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale 780,000  
Real estate loans [Member] | Impaired Loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,900,000 8,700,000
Commercial and industrial loans [Member] | Non-Performing Loans Held for Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-performing loans held for sale 1,800,000  
Commercial and industrial loans [Member] | Impaired Loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 22,400,000 27,000,000
Consumer loans [Member] | Impaired Loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans $ 1,300,000 $ 1,000,000