Allowance for Loan Losses - Internal Risk Rating Grades (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
INTERNAL RISK RATING GRADES
Loan Receivables	$ 144,783	$ 132,038
Pass
INTERNAL RISK RATING GRADES
Loan Receivables	120,993	107,475
Watch
INTERNAL RISK RATING GRADES
Loan Receivables	15,485	16,341
Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	4,396	4,346
Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	3,909	3,876
Construction, Land and Land Development
INTERNAL RISK RATING GRADES
Loan Receivables	44,571	43,048
Construction, Land and Land Development | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	36,909	34,913
Construction, Land and Land Development | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	5,441	5,649
Construction, Land and Land Development | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	1,146	1,403
Construction, Land and Land Development | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,075	1,083
Farmland
INTERNAL RISK RATING GRADES
Loan Receivables	1,054	1,128
Farmland | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	1,054	1,128
Commercial Mortgages (Non-Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	23,799	20,534
Commercial Mortgages (Non-Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	18,807	16,426
Commercial Mortgages (Non-Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,444	3,770
Commercial Mortgages (Non-Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	284
Commercial Mortgages (Non-Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	264	338
Commercial Mortgages (Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	41,723	33,326
Commercial Mortgages (Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	32,443	23,967
Commercial Mortgages (Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,103	4,430
Commercial Mortgages (Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	2,697	2,789
Commercial Mortgages (Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,480	2,140
Commercial and Industrial
INTERNAL RISK RATING GRADES
Loan Receivables	33,636	34,002
Commercial and Industrial | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	31,780	31,041
Commercial and Industrial | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,497	2,492
Commercial and Industrial | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	269	154
Commercial and Industrial | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	$ 90	$ 315