Aging of Recorded Investment in Loans by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	$ 5,289	$ 6,711
60-89 Days Past Due	842	1,003
Over 90 Days Past Due	2,231	2,326
Total Past Due	8,362	10,040
Current	273,114	276,196
Recorded investment in loans	281,476	286,236
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	3,989	4,085
60-89 Days Past Due	347	871
Over 90 Days Past Due	1,587	1,644
Total Past Due	5,923	6,600
Current	99,879	102,003
Recorded investment in loans	105,802	108,603
Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	187	343
60-89 Days Past Due	135	0
Over 90 Days Past Due	136	119
Total Past Due	458	462
Current	8,979	9,195
Recorded investment in loans	9,437	9,657
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	0	171
60-89 Days Past Due	0	0
Over 90 Days Past Due	111	113
Total Past Due	111	284
Current	11,704	11,479
Recorded investment in loans	11,815	11,763
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	178	360
60-89 Days Past Due	334	0
Over 90 Days Past Due	125	335
Total Past Due	637	695
Current	68,931	68,207
Recorded investment in loans	69,568	68,902
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	237	36
60-89 Days Past Due	0	0
Over 90 Days Past Due	0	0
Total Past Due	237	36
Current	18,136	18,619
Recorded investment in loans	18,373	18,655
Home Equity and Second Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	411	1,206
60-89 Days Past Due	0	102
Over 90 Days Past Due	263	97
Total Past Due	674	1,405
Current	34,864	35,881
Recorded investment in loans	35,538	37,286
Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	287	510
60-89 Days Past Due	26	30
Over 90 Days Past Due	9	18
Total Past Due	322	558
Current	30,621	30,812
Recorded investment in loans	$ 30,943	$ 31,370