Loans and Allowance for Loan Losses - Additional Information (Detail)	Jun. 30, 2015 USD ($) Loans	Dec. 31, 2014 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Impaired loans, net	$ 670,000	$ 616,000
Troubled debt restructurings subsequently default within twelve months	$ 1,000,000	0
Troubled debt restructuring number of loans \| Loans	1
Consumer mortgage loans	$ 601,000
Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Potential problem loans	$ 34,100,000	$ 35,800,000

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3),(b))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5111-111524

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- Definition

Loans where the borrowers have experienced financial difficulty and the Company has identified as a potential future loss. Additional monitoring is administered to these loans.

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