Purchase and Assumption - Additional Information (Detail) (USD $)	Sep. 30, 2012	Feb. 10, 2012
Business Acquisition [Line Items]
Assets Acquired		$ 147,700,000
Cash and cash equivalents		11,900,000
Marketable securities		18,896,000
Federal Home Loan Bank stock		1,800,000
Loans	113,000,000	113,000,000
Premises and other assets		2,100,000
Liabilities absorbed		135,700,000
Customer deposits		125,700,000
Other Borrowed money		9,600,000
Other Liabilities		402,000
Assets acquired, discount		29,000,000
Difference between the purchase price of the assets acquired and the value of the liabilities assumed		17,200,000
Loan portfolio acquired, fair value discount	19,200,000
Performing portion of loan portfolio, fair value		93,793,000
Loans Receivable
Business Acquisition [Line Items]
Loans		86,300,000
Loan portfolio acquired, fair value discount		19,200,000
Performing portion of loan portfolio, fair value		$ 76,500,000