Recorded Investment in Loans for Each Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	$ 293,544	$ 284,941
Accrued interest receivable	990	1,093
Net deferred loan origination fees and costs	297	202
Recorded investment in loans	294,831	286,236
Individually evaluated for impairment	4,679	7,583
Collectively evaluated for impairment	290,152	278,653
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	294,831	286,236
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	108,317	108,097
Accrued interest receivable	423	444
Net deferred loan origination fees and costs	50	62
Recorded investment in loans	108,790	108,603
Individually evaluated for impairment	1,380	2,370
Collectively evaluated for impairment	107,410	106,233
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	108,790	108,603
Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	10,090	9,607
Accrued interest receivable	49	48
Net deferred loan origination fees and costs	2	2
Recorded investment in loans	10,141	9,657
Individually evaluated for impairment	123	125
Collectively evaluated for impairment	10,018	9,532
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	10,141	9,657
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	9,734	11,746
Accrued interest receivable	18	29
Net deferred loan origination fees and costs	0	(12)
Recorded investment in loans	9,752	11,763
Individually evaluated for impairment	0	403
Collectively evaluated for impairment	9,752	11,360
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	9,752	11,763
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	77,820	68,731
Accrued interest receivable	179	188
Net deferred loan origination fees and costs	(34)	(17)
Recorded investment in loans	77,965	68,902
Individually evaluated for impairment	1,102	2,836
Collectively evaluated for impairment	76,863	66,066
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	77,965	68,902
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	20,049	18,612
Accrued interest receivable	42	53
Net deferred loan origination fees and costs	(9)	(10)
Recorded investment in loans	20,082	18,655
Individually evaluated for impairment	1,968	1,776
Collectively evaluated for impairment	18,114	16,879
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	20,082	18,655
Home Equity and Second Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	34,614	36,962
Accrued interest receivable	124	147
Net deferred loan origination fees and costs	288	177
Recorded investment in loans	35,026	37,286
Individually evaluated for impairment	106	73
Collectively evaluated for impairment	34,920	37,213
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	35,026	37,286
Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal loan balance	32,920	31,186
Accrued interest receivable	155	184
Net deferred loan origination fees and costs	0	0
Recorded investment in loans	33,075	31,370
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	33,075	31,370
Acquired with deteriorated credit quality	0	0
Recorded investment in loans	$ 33,075	$ 31,370