Securities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2011
Gain (Loss) on Investments [Line Items]
Business acquisition, effective date of acquisition of American Community Bancorp, Inc.	Jan. 01, 2011
Gain recognized on stock held as a result of acquisition	$ 1,045

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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

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