Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Commercial Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	3,828	3,803
Commercial Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Commercial 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%
Commercial Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	20.00%	20.00%
Commercial Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(10.00%)	(10.00%)
Residential Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	406	765
Residential Loans [Member] | Sales Comparison Approach [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Valuation Technique	Sales comparison approach	Sales comparison approach
Residential 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%
Residential Loans [Member] | Sales Comparison Approach [Member] | Maximum [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	10.77%	11.80%
Residential Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(10.00%)	(3.70%)
Consumer Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	276	260
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	17.85%	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	(17.85%)	(5.00%)
Permanent Real Estate Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	626	640
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%	0.00%
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	40.50%	51.10%
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	(10.93%)	(26.83%)
Construction Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value	1,013	1,286
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%	0.00%
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%	58.10%
Construction Loans [Member] | Sales Comparison Approach [Member] | Weighted Average [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Adjustment for differences between comparable sales	(18.76%)	(22.20%)