Recorded Investment in Loans by Risk Category (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	$ 286,626	$ 281,356
Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	261,431	258,826
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	9,214	8,385
Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	7,989	6,744
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	7,992	7,401
Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Residential
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	112,105	116,868
Residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	105,004	113,037
Residential | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,113	862
Residential | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,290	688
Residential | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,698	2,281
Residential | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Land
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	9,707	9,972
Land | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	7,306	7,578
Land | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	268	255
Land | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,129	2,134
Land | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	4	5
Land | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Construction
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	11,896	6,979
Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	11,303	6,217
Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	199	307
Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	208
Construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	394	247
Construction | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	64,106	57,840
Commercial Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	53,670	46,544
Commercial Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	4,917	5,392
Commercial Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,533	3,051
Commercial Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,986	2,853
Commercial Real Estate | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	19,192	20,776
Commercial Business | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	15,264	16,961
Commercial Business | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,526	1,462
Commercial Business | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	593	425
Commercial Business | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,809	1,928
Commercial Business | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Home Equity and Second Mortgage
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	37,644	38,887
Home Equity and Second Mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	37,009	38,513
Home Equity and Second Mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	136	63
Home Equity and Second Mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	398	224
Home Equity and Second Mortgage | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	101	87
Home Equity and Second Mortgage | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Other Consumer
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	31,976	30,034
Other Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	31,875	29,976
Other Consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	55	44
Other Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	46	14
Other Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Other Consumer | Unlikely to be Collected Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	$ 0	$ 0