Income Taxes - Schedule of Difference Between Income Tax Expense and Amount Computed by Applying Statutory Federal Income Tax Rate to Income Before Taxes (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Tax Disclosure [Abstract]      
Pretax income at statutory rate $ 3,085 $ 2,147 $ 1,064
State income tax expense, net 224 251 125
Cash surrender value income (83) (80) (66)
Tax exempt interest (65) (56) (68)
Minority interest (174)    
Merger related expenses 111    
Change in valuation allowance (12)    
Other 73 48 16
Income tax expense $ 3,159 $ 2,310 $ 1,071