Fair Value - Schedule of Fair Value Level III Assets Measured at Fair Value on a Recurring or Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation Technique	Appraisal of collateral
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Assets	$ 16,177	$ 14,740
Valuation Technique	Discounted Cash Flow
Significant Unobservable Inputs	Remaining term
Impaired Loans [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0 years
Impaired Loans [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	27 years 2 months 12 days
Impaired Loans [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	24 years
Servicing Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Assets	8	14
Valuation Technique	Discounted Cash Flow
Significant Unobservable Inputs	Remaining term
Servicing Assets [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	2 months 12 days
Servicing Assets [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	18 years
Servicing Assets [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	12 years
Real Estate Acquired Through Foreclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Assets	1,977	2,441
Valuation Technique	Appraisal of collateral (1)
Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Assets	36,768	36,179
Valuation Technique	Discounted Cash Flow
Trust Preferred Securities Credit Spreads [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Credit Spreads
Trust Preferred Securities Credit Spreads [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.45%
Trust Preferred Securities Credit Spreads [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.75%
Trust Preferred Securities Credit Spreads [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.625%
Trust Preferred Securities Liquidity Risk Adjustments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Liquidity Risk Adjustments
Trust Preferred Securities Liquidity Risk Adjustments [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.20%
Trust Preferred Securities Liquidity Risk Adjustments [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.55%
Trust Preferred Securities Liquidity Risk Adjustments [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.36%
Trust Preferred Securities Default Rates [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Default Rates
Trust Preferred Securities Default Rates [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	0.60%
Trust Preferred Securities Default Rates [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	1.00%
Impaired Loans Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Discount Rate
Impaired Loans Discount Rate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	3.625%
Impaired Loans Discount Rate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	16.30%
Impaired Loans Discount Rate [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	6.42%
Impaired Loans Appraisal Adjustment and Liquidation Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Appraisal adj and liquidation exp
Impaired Loans Appraisal Adjustment and Liquidation Expense [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	2,000
Impaired Loans Appraisal Adjustment and Liquidation Expense [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	$ 500,000
Servicing Assets Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant Unobservable Inputs	Discount Rate
Servicing Assets Discount Rate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	11.25%
Servicing Assets Discount Rate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	12.25%
Servicing Assets Discount Rate [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range/Weighted Average	11.51%