Other Borrowings - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Borrowing available with FHLB	$ 70.6
Credit arrangements for federal funds purchase	60
Loans pledged at Federal Reserve discount window	362.5
Loans pledged at Federal Reserve discount window available for borrowing	$ 267.8

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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