Loans - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net unearned income and deferred fees	$ 426,000	$ 320,000
Lendable Collateral	84,900,000	79,900,000
Additional Interest Income	155,000
Interest income recognized on impaired loans	398,000
Average balance of total impaired loans	43,600,000
Federal Home Loan Bank Advances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans were pledged to collateralize FHLB	210,900,000	201,200,000
Federal Reserve System Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans were pledged to collateralize FHLB	$ 2,300,000	$ 2,500,000

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

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The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.

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- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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