Loans - Schedule of Aging of Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 409,549	$ 405,220
Non-Accrual	1,864	3,668
Total Past Due and Non-Accrual	3,022	5,331
Total ending loans balance	412,571	410,551
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	861	1,033
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	143	349
90 Days Plus Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	154	281
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	125,306	122,283
Non-Accrual	203	1,071
Total Past Due and Non-Accrual	479	1,530
Total ending loans balance	125,785	123,813
Commercial [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	262	362
Commercial [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14	96
Commercial [Member] | 90 Days Plus Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	139,240	137,683
Non-Accrual	908	1,734
Total Past Due and Non-Accrual	970	2,012
Total ending loans balance	140,210	139,695
Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	62	174
Commercial Real Estate [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		104
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	120,595	120,025
Non-Accrual	753	863
Total Past Due and Non-Accrual	1,435	1,659
Total ending loans balance	122,030	121,684
Residential Real Estate [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	437	424
Residential Real Estate [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	91	92
Residential Real Estate [Member] | 90 Days Plus Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	154	280
Construction & Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	15,188	17,431
Total Past Due and Non-Accrual		15
Total ending loans balance	15,188	17,446
Construction & Land Development [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		15
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9,220	7,798
Total Past Due and Non-Accrual	138	115
Total ending loans balance	9,358	7,913
Consumer [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	100	73
Consumer [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 38	$ 42