Investment Securities - Additional Information (Detail) (USD $)	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities amortized cost	$ 57,929,000		$ 58,011,000
Proceeds from sale, maturities and call of Securities Available for Sale	8,700,000	13,000,000
Gain (loss) on sale or call of available for sale securities	0	10,000
Estimated fair value of securities pledged to secure public funds; securities sold under agreements to repurchase and for other purposes	27,500,000	26,000,000
Available for sale securities estimated fair value	57,504,000		57,336,000
Collateralized Mortgage Obligations
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities amortized cost	7,872,000		7,823,000
Available for sale securities estimated fair value	7,948,000		7,892,000
Mortgage Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities amortized cost	13,456,000		12,932,000
Available for sale securities estimated fair value	13,809,000		13,179,000
Asset Backed Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities amortized cost	2,578,000		2,548,000
Fair value of investment	100,000		100,000
Fair value as percentage of available for sale investment portfolio	0.10%		0.10%
Available for sale securities estimated fair value	68,000		68,000
Collateralized Debt Obligations
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities amortized cost	2,200,000
Available for sale securities estimated fair value	$ 100,000

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

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- Definition

The cash inflow associated with the sale or maturity (principal being due) of securities not classified as either held-to-maturity securities or trading securities which are classified as available-for-sale securities.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 16

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 16

-Subparagraph a

-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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 18

-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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 45

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