Allowance for Loan Losses - Internal Risk Rating Grades (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
INTERNAL RISK RATING GRADES
Loan Receivables	$ 169,332	$ 161,033
Pass
INTERNAL RISK RATING GRADES
Loan Receivables	144,841	135,703
Watch
INTERNAL RISK RATING GRADES
Loan Receivables	19,407	18,522
Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	489	2,030
Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	4,595	4,778
Construction, Land and Land Development
INTERNAL RISK RATING GRADES
Loan Receivables	44,119	39,818
Construction, Land and Land Development | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	36,423	32,009
Construction, Land and Land Development | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	5,762	5,795
Construction, Land and Land Development | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	179	180
Construction, Land and Land Development | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,755	1,834
Farmland
INTERNAL RISK RATING GRADES
Loan Receivables	994	1,023
Farmland | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	994	1,023
Commercial Mortgages (Non-Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	35,464	35,343
Commercial Mortgages (Non-Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	30,571	30,639
Commercial Mortgages (Non-Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,375	4,184
Commercial Mortgages (Non-Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	270	272
Commercial Mortgages (Non-Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	248	248
Commercial Mortgages (Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	42,550	41,825
Commercial Mortgages (Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	32,412	31,191
Commercial Mortgages (Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	7,732	6,652
Commercial Mortgages (Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables		1,453
Commercial Mortgages (Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,406	2,529
Commercial and Industrial
INTERNAL RISK RATING GRADES
Loan Receivables	46,205	43,024
Commercial and Industrial | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	44,441	40,841
Commercial and Industrial | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,538	1,891
Commercial and Industrial | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	40	125
Commercial and Industrial | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	$ 186	$ 167