Assets Pledged - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013	Dec. 31, 2012
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt securities pledged by bank as collateral	$ 58.9	$ 62.7
Securities pledged as collateral, description	The Bank pledges as collateral for Federal Home Loan Bank (the "FHLB") advances commercial and residential real estate mortgage loans under a collateral agreement with the FHLB whereby the Bank maintains, free of other encumbrances, qualifying mortgages (as defined) with unpaid principal balances equal to, when discounted at 75% of the unpaid principal balances, 100% of total advances.

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)(1)(i)

-URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant