Credit Quality Assessment - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable Troubled Debt Restructurings Balance	$ 1,552,000	$ 4,918,000
Financing Receivable Troubled Debt Restructurings Specific Allowance	55,000	1,223,000
Available Portion of Contractual Agreements to Lend Additional Financing	5,500,000	2,600,000
Repossessed Assets, Total	$ 4,831,000	$ 5,926,000