Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Provisions for loan losses	$ 225,000	$ 300,000	$ 475,000	$ 775,000
Impaired Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Provisions for loan losses	0		45,000
Impaired Loans | Level 3 | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, discount rate			10.00%
Fair value measurement, estimated costs to sell the collateral			10.00%
Impaired Loans | Level 3 | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, discount rate			20.00%
Fair value measurement, estimated costs to sell the collateral			15.00%
Foreclosed Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed real estate write down charges	$ 0		$ 32,000
Foreclosed Real Estate | Level 3 | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, discount rate			10.00%
Fair value measurement, estimated costs to sell the collateral			10.00%
Foreclosed Real Estate | Level 3 | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement, discount rate			20.00%
Fair value measurement, estimated costs to sell the collateral			15.00%