Fair Value Measurements - Summary of Quantitative Fair Value Measurements for Level 3 (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impaired Loans, net	$ 2,690	$ 1,958
Other real estate owned, net	2,343	2,791
Impaired Loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impaired Loans, net	2,690	1,958
Other Real Estate Owned
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other real estate owned, net	$ 2,343	$ 2,791
Minimum | Impaired Loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	10.00%	10.00%
Unobservable Input, Lack of Marketability	25.00%	25.00%
Minimum | Other Real Estate Owned
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	3.00%	3.00%
Unobservable Input, Lack of Marketability	7.00%	7.00%
Maximum | Impaired Loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	25.00%	20.00%
Unobservable Input, Lack of Marketability	75.00%	75.00%
Maximum | Other Real Estate Owned
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	13.00%	13.00%
Unobservable Input, Lack of Marketability	20.00%	20.00%
Weighted Average | Impaired Loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	13.00%	10.00%
Unobservable Input, Lack of Marketability	52.00%	53.00%
Weighted Average | Other Real Estate Owned
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input, Selling Cost	5.00%	5.00%
Unobservable Input, Lack of Marketability	10.00%	11.00%