Credit Risk Profile by Creditworthiness Category (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	$ 9,120	[1]	$ 9,024	[1]
Commercial real estate	74,383	[1]	75,210	[1]
Superior Quality
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	53	[1]	58	[1]
Satisfactory
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	215	[1]	209	[1]
Commercial real estate	6,565	[1]	7,238	[1]
Grade 4 Acceptable Risk
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	3,379	[1]	4,148	[1]
Commercial real estate	25,928	[1]	24,844	[1]
Grade 5 Watch
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	2,631	[1]	2,433	[1]
Commercial real estate	27,316	[1]	23,762	[1]
Grade 6 Special Mention
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	1,165	[1]	1,125	[1]
Commercial real estate	3,930	[1]	6,860	[1]
Grade 7 Substandard
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	1,582	[1]	957	[1]
Commercial real estate	9,394	[1]	11,256	[1]
Grade 8 Doubtful
Financing Receivable, Recorded Investment [Line Items]
Commercial non real Estate	95	[1]	94	[1]
Commercial real estate	$ 1,250	[1]	$ 1,250	[1]

[1] Credit quality indicators are reviewed and updated as applicable on an ongoing basis in accordance with credit policies.