Loans And Allowance For Loan Losses - Additional Information (Detail) (USD $)	9 Months Ended		9 Months Ended	12 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Fixed Rate Residential Mortgage	Dec. 31, 2011 Fixed Rate Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans sold on secondary market				$ 18,800,000	$ 28,600,000
Gain (loss) on sale of mortgage loans	268,000	203,000		268,000	292,000
Loans restructured due to credit difficulties that are now performing	3,200,000		3,300,000
Allowance for credit Losses related to troubled debt restructuring	$ 395,000		$ 357,000

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_GainLossOnSaleOfMortgageLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration