Additional Detail of Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Outstanding Recorded Investment Pre-Modification	$ 107	$ 212
Outstanding Recorded Investment Post - Modification	107	212
Number of Loans	1	3
Interest Income Recognized	7	39	134
Consumer real estate
Financing Receivable, Modifications [Line Items]
Outstanding Recorded Investment Pre-Modification		63
Outstanding Recorded Investment Post - Modification		63
Number of Loans		1
Interest Income Recognized		12	15
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Outstanding Recorded Investment Pre-Modification	107	107
Outstanding Recorded Investment Post - Modification	107	107
Number of Loans	1	1
Interest Income Recognized	7	21	108
Consumer Installment [Member]
Financing Receivable, Modifications [Line Items]
Outstanding Recorded Investment Pre-Modification		42
Outstanding Recorded Investment Post - Modification		42
Number of Loans		1
Interest Income Recognized		$ 1

Financing Receivable, Modifications, Number of Contracts, During Period

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- Definition

Financing Receivable, Modifications, Post-Modification Recorded Investment During Period

+ References

No definition available.

+ Details

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- Definition

Financing Receivable, Modifications, Pre-Modification Recorded Investment During Period

+ References

No definition available.

+ Details

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5212-111524

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