Recorded Investment in Loans by Risk Category (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	$ 281,476	$ 286,236
Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	264,909	266,540
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	3,772	4,041
Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	6,975	8,072
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	5,820	7,583
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	105,802	108,603
Residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	100,748	102,618
Residential | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	879	958
Residential | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,201	2,657
Residential | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,974	2,370
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	9,437	9,657
Land | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	6,916	7,220
Land | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	115	17
Land | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	2,276	2,295
Land | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	130	125
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	11,815	11,763
Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	11,306	11,244
Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	249	116
Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	0	0
Construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	260	403
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	69,568	68,902
Commercial Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	65,293	63,095
Commercial Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,097	1,018
Commercial Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,772	1,953
Commercial Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,406	2,836
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	18,373	18,655
Commercial Business | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	15,236	15,026
Commercial Business | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	903	1,354
Commercial Business | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	458	499
Commercial Business | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	1,776	1,776
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	35,538	37,286
Home Equity and Second Mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	34,489	36,035
Home Equity and Second Mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	515	553
Home Equity and Second Mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	260	625
Home Equity and Second Mortgage | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	274	73
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	30,943	31,370
Other Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	30,921	31,302
Other Consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	14	25
Other Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in loans	8	43
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