Aging of Recorded Investment in Loans by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	$ 6,181	$ 7,443
60-89 Days Past Due	1,722	1,220
Over 90 Days Past Due	1,666	2,852
Total Past Due	9,569	11,515
Current	277,057	269,841
Recorded investment in loans	286,626	281,356
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	4,618	5,205
60-89 Days Past Due	1,377	1,068
Over 90 Days Past Due	1,122	1,035
Total Past Due	7,117	7,308
Current	104,988	109,560
Recorded investment in loans	112,105	116,868
Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	301	442
60-89 Days Past Due	4	43
Over 90 Days Past Due	0	43
Total Past Due	305	528
Current	9,402	9,444
Recorded investment in loans	9,707	9,972
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	113	0
60-89 Days Past Due	141	0
Over 90 Days Past Due	0	247
Total Past Due	254	247
Current	11,642	6,732
Recorded investment in loans	11,896	6,979
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	244	676
60-89 Days Past Due	0	0
Over 90 Days Past Due	443	1,258
Total Past Due	687	1,934
Current	63,419	55,906
Recorded investment in loans	64,106	57,840
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	8	256
60-89 Days Past Due	17	0
Over 90 Days Past Due	0	0
Total Past Due	25	256
Current	19,167	20,520
Recorded investment in loans	19,192	20,776
Home Equity and Second Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	584	558
60-89 Days Past Due	140	72
Over 90 Days Past Due	69	246
Total Past Due	793	876
Current	36,851	38,011
Recorded investment in loans	37,644	38,887
Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	313	306
60-89 Days Past Due	43	37
Over 90 Days Past Due	32	23
Total Past Due	388	366
Current	31,588	29,668
Recorded investment in loans	$ 31,976	$ 30,034