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Allowance for Loan Losses - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract	Jun. 30, 2013 Contract D	Jun. 30, 2012 Contract	Dec. 31, 2012
Receivables [Abstract]
Troubled debt restructurings (TDRs)			$ 2,200,000		$ 6,300,000
TDRs performing under the restructured terms	838,000		838,000		1,600,000
New loans modified under TDRs	0	0	0	0
Troubled debt restructuring loan subsequent default	$ 0	$ 0	$ 0	$ 0
Troubled debt restructuring loan subsequent default period			90

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Financing Receivable Modification As Troubled Debt Restructuring That Subsequently Defaulted

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Financing receivable subsequent default recorded investment.

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Performing troubled debt restructurings.

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524

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Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524

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