Assets and Liabilities Measured at Estimated Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	$ 57,436		$ 57,268
Level 2 | Fair Value, Measurements, Recurring | Mortgage Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	21,757		21,071
Level 2 | Fair Value, Measurements, Recurring | US Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	23,859		24,606
Level 2 | Fair Value, Measurements, Recurring | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	11,820		11,591
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	9,512		6,987
Level 3 | Fair Value, Measurements, Recurring | Asset Backed Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	68		68
Level 3 | Fair Value, Measurements, Nonrecurring | Impaired Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	7,834	[1]	6,304	[1]
Level 3 | Fair Value, Measurements, Nonrecurring | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	$ 1,610	[2]	$ 615	[2]

[1] Includes loans that have been measured for impairment at the fair value of the loans' collateral.

[2] Other real estate owned is transferred from loans to OREO at the lower of cost or market.