Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Detail)

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Fair Value Measurements - Additional Information (Detail) (USD $)
6 Months Ended
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Tax credit to be received 1 year 8 months 12 days          
Percentage of decline in bond value 0.89%          
Loans held for sale $ 2,553,000 $ 6,043,000 $ 8,306,000 $ 5,138,000 $ 55,993,000 $ 22,587,000
Zero Coupon Municipal Bond [Member]
           
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Zero coupon tax credit municipal bond, recorded at estimated fair value 762,000   779,000      
Significant Observable Inputs with No Active Market with Identical Characteristics [Member] | Non-recurring Basis [Member] | Small Business Administration Loans Held for Sale [Member]
           
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Loans held for sale 0   7,800,000      
Significant Observable Inputs with No Active Market with Identical Characteristics [Member] | Non-recurring Basis [Member] | Non-Performing Loans Held for Sale [Member]
           
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Loans held for sale $ 2,600,000   $ 484,000