Allowance for Loan Losses - Internal Risk Rating Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
INTERNAL RISK RATING GRADES
Loan Receivables	$ 161,033	$ 151,305
Pass
INTERNAL RISK RATING GRADES
Loan Receivables	135,703	122,386
Watch
INTERNAL RISK RATING GRADES
Loan Receivables	18,522	20,071
Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	2,030	3,954
Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	4,778	4,894
Construction, Land and Land Development
INTERNAL RISK RATING GRADES
Loan Receivables	39,818	42,129
Construction, Land and Land Development | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	32,009	34,692
Construction, Land and Land Development | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	5,795	5,337
Construction, Land and Land Development | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	180	1,119
Construction, Land and Land Development | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,834	981
Farmland
INTERNAL RISK RATING GRADES
Loan Receivables	1,023	1,030
Farmland | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	1,023	1,030
Commercial Mortgages (Non-Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	35,343	29,086
Commercial Mortgages (Non-Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	30,639	24,258
Commercial Mortgages (Non-Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,184	4,564
Commercial Mortgages (Non-Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	272
Commercial Mortgages (Non-Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	248	264
Commercial Mortgages (Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	41,825	43,956
Commercial Mortgages (Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	31,191	33,023
Commercial Mortgages (Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	6,652	4,968
Commercial Mortgages (Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	1,453	2,687
Commercial Mortgages (Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,529	3,278
Commercial and Industrial
INTERNAL RISK RATING GRADES
Loan Receivables	43,024	35,104
Commercial and Industrial | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	40,841	29,383
Commercial and Industrial | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,891	5,202
Commercial and Industrial | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	125	148
Commercial and Industrial | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	$ 167	$ 371