Preferred Stock - Additional Information (Detail) (USD $)	1 Months Ended	6 Months Ended
	Mar. 13, 2009	Jun. 30, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Preferred stock issued		9,266	9,266
Preferred Stock, liquidation preference per share	$ 1,000
Exercise price of warrant	7.77
Proceed from issuance of preferred stock and warrant	$ 9,300,000
Increase in Additional paid-in-capital due to allotment to warrants	25,000
Period in which warrant to be exercised	10 years
Amortization period for amount allocated to warrant	5 years
Preferred Stock, Dividend Payment Terms		Under the terms of the TARP Preferred Stock, the Corporation is required to pay on a quarterly basis a dividend rate of 5% per year for the first five years, after which the dividend rate automatically increases to 9% per year. Dividend payments may be deferred, but the dividend is cumulative and failure to pay dividends for six dividend periods may trigger board appointment rights for the holder of the TARP Preferred Stock.
Total deferred dividends		$ 1,200,000
First five years
Class of Stock [Line Items]
Dividend Rate		5.00%
After five years
Class of Stock [Line Items]
Dividend Rate		9.00%
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock issued	9,266
Maximum
Class of Stock [Line Items]
Common stock purchase warrant	178,880