Loans - Internal Risk Rating Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
INTERNAL RISK RATING GRADES
Loan Receivables	$ 902,345	$ 766,296
Pass
INTERNAL RISK RATING GRADES
Loan Receivables	838,340	688,214
Watch
INTERNAL RISK RATING GRADES
Loan Receivables	52,158	64,987
Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	2,260	1,724
Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	9,587	11,371
Construction, Land and Land Development
INTERNAL RISK RATING GRADES
Loan Receivables	108,767	66,042
Construction, Land and Land Development | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	100,299	55,949
Construction, Land and Land Development | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	6,299	6,690
Construction, Land and Land Development | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	68	172
Construction, Land and Land Development | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,101	3,231
Farmland
INTERNAL RISK RATING GRADES
Loan Receivables	708	923
Farmland | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	708	923
Commercial Mortgages (Non-Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	180,074	146,757
Commercial Mortgages (Non-Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	174,661	140,625
Commercial Mortgages (Non-Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,275	5,931
Commercial Mortgages (Non-Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,138	201
Commercial Mortgages (Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	87,241	80,052
Commercial Mortgages (Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	79,375	67,732
Commercial Mortgages (Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	6,522	10,076
Commercial Mortgages (Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	107
Commercial Mortgages (Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,237	2,244
Residential First Mortgages
INTERNAL RISK RATING GRADES
Loan Receivables	298,894	269,365
Residential First Mortgages | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	280,663	256,614
Residential First Mortgages | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	14,709	8,624
Residential First Mortgages | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	1,071	205
Residential First Mortgages | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,451	3,922
Residential Revolving and Junior Mortgages
INTERNAL RISK RATING GRADES
Loan Receivables	38,313	46,498
Residential Revolving and Junior Mortgages | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	35,900	43,659
Residential Revolving and Junior Mortgages | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,306	1,376
Residential Revolving and Junior Mortgages | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,107	1,463
Commercial and Industrial
INTERNAL RISK RATING GRADES
Loan Receivables	164,608	114,093
Commercial and Industrial | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	158,590	110,281
Commercial and Industrial | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	3,802	2,373
Commercial and Industrial | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	893	1,347
Commercial and Industrial | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,323	92
Consumer
INTERNAL RISK RATING GRADES
Loan Receivables	23,740	42,566
Consumer | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	8,144	12,431
Consumer | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	15,245	29,917
Consumer | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	121
Consumer | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	$ 230	$ 218