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) (Nonrecurring Basis [Member], USD $)
Mar. 31, 2013
Dec. 31, 2012
Nonperforming loans held for sale [Member] | Small Business Administration Loans Held for Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-Performing Loans Held for sale $ 484,000,000 $ 484,000
Nonperforming loans held for sale [Member] | Commercial term loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-Performing Loans Held for sale 1,800,000  
Impaired Loans [Member] | Real estate loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired Loans 4,000,000 8,700,000
Impaired Loans [Member] | Commercial and Industrial Loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired Loans 21,000,000 27,000,000
Impaired Loans [Member] | Consumer Loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired Loans 900,000 1,000,000
Other Real Estate Owned [Member] | Small Business Administration Loans Held for Sale [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-Performing Loans Held for sale 387,000  
Other Real Estate Owned [Member] | Real estate loans [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-Performing Loans Held for sale   774,000
Other Real Estate Owned [Member] | Commercial property loan [Member]
    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Non-Performing Loans Held for sale $ 513,000