Investment Securities - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Total fair value of investments securities, less than historical cost	$ 10,813,000		$ 10,813,000		$ 12,122,000
Total fair value of investments securities, less than historical cost, percentage of portfolio	17.30%		17.30%		22.00%
Market value of pledged investment securities	$ 22,837,000		$ 22,837,000		$ 8,499,000
Sale of available-for-sale securities	$ 0	$ 0	$ 0	$ 0

Company investment portfolio percentage.

No definition available.

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- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

+ Details

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Period Type:	duration

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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- Definition

The fair value, as of the date of each statement of financial position presented, of securities which are owned but transferred to serve as collateral for the payment of repurchase agreements, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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