Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 268	$ 546
Valuation Technique	Discounted cash flow	Discounted cash flow
Impaired Loans Permanent Real Estate Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	2,751	2,219
Impaired Loans Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Impaired Loans Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	5.00%	0.00%
Impaired Loans Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	20.00%	56.90%
Impaired Loans Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(12.50%)	11.78%
Impaired Loans Permanent Real Estate Loans [Member] | Income Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Income approach	Income approach
Impaired Loans Permanent Real Estate Loans [Member] | Income Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	4.70%	3.95%
Impaired Loans Permanent Real Estate Loans [Member] | Income Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	11.94%	14.62%
Impaired Loans Permanent Real Estate Loans [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences in net operating income Capitalization rate	(9.50%)	9.41%
Impaired Loans Construction [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	1,899	1,587
Impaired Loans Construction [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Impaired Loans Construction [Member] | Sales Comparison Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Impaired Loans Construction [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	20.00%	25.00%
Impaired Loans Construction [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(10.00%)	11.90%
Consumer Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	249	339
Consumer Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Consumer Loans [Member] | Sales Comparison Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	0.00%
Consumer Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	10.00%	10.00%
Consumer Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(5.00%)	5.00%
Permanent Real Estate Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	1,073	1,939
Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	6.00%
Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	51.10%	46.53%
Permanent Real Estate Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(26.83%)	17.76%
Construction Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	$ 1,698	$ 2,310
Construction Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Construction Loans [Member] | Sales Comparison Approach [Member] | Minimum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	0.00%	6.54%
Construction Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	53.10%	26.63%
Construction Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(22.20%)	9.24%