Loans and Allowance for Loan and Lease Losses - Loan Portfolio Aging Analysis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	$ 1,536	$ 1,436
60-89 Days Past Due	68	536
90 Days and Greater	3,541	3,364
Total Past Due	5,145	5,336
Current	319,578	315,689
Total	324,723	321,025
Total Loans greater than 90 days and Accruing	1	15
Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Greater	812	812
Total Past Due	812	812
Current	113,319	110,643
Total	114,131	111,455
Residential Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,155	1,346
60-89 Days Past Due	67	212
90 Days and Greater	1,775	1,598
Total Past Due	2,997	3,156
Current	157,983	160,683
Total	160,980	163,839
Total Loans greater than 90 days and Accruing		14
Construction Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 Days and Greater	836	836
Total Past Due	836	836
Current	17,558	12,734
Total	18,394	13,570
Commercial Loans and Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	379	80
60-89 Days Past Due		320
90 Days and Greater	117	117
Total Past Due	496	517
Current	26,854	28,841
Total	27,350	29,358
Municipal Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,895	785
Total	1,895	785
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2	10
60-89 Days Past Due	1	4
90 Days and Greater	1	1
Total Past Due	4	15
Current	1,969	2,003
Total	1,973	2,018
Total Loans greater than 90 days and Accruing	$ 1	$ 1