Fair Value - Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Non Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Impaired Loans - Commercial Mortgages [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair value

$ 3,000

$ 8,422

Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair value

3,274

Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Income Approach Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair value

432

1,973

Impaired Loans - Residential Real Estate [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair value

$ 402

Minimum [Member] | Impaired Loans - Commercial Mortgages [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

17.00%

1.00%

Minimum [Member] | Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Income Approach Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Income approach

24.00%

Minimum [Member] | Impaired Loans - Residential Real Estate [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

10.00%

Maximum [Member] | Impaired Loans - Commercial Mortgages [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

61.00%

39.00%

Maximum [Member] | Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Income Approach Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Income approach

38.00%

Maximum [Member] | Impaired Loans - Residential Real Estate [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

15.00%

Weighted Average [Member] | Impaired Loans - Commercial Mortgages [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

22.00%

(19.00%)

Weighted Average [Member] | Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

9.00%

Weighted Average [Member] | Impaired Loans - Commercial, Industrial, and Agricultural [Member] | Income Approach Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Income approach

2.00%

(27.00%)

Weighted Average [Member] | Impaired Loans - Residential Real Estate [Member] | Sales Comparison Valuation Technique [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Sales comparison approach

(11.00%)