Summary of Stock Options Activity and Related Information (Detail)	6 Months Ended
Jun. 30, 2017 $ / shares shares
Options
Beginning balance \| shares	20,000
Granted \| shares	0
Canceled \| shares	0
Exercised \| shares	0
Expired/Forfeited \| shares	0
Ending balance \| shares	20,000
Exercisable at June 30, 2017 \| shares	20,000
Weighted Average Exercise Price
Beginning balance \| $ / shares	$ 12.29
Granted \| $ / shares	0
Canceled \| $ / shares	0
Exercised \| $ / shares	0
Expired/Forfeited \| $ / shares	0
Ending balance \| $ / shares	12.29
Exercisable at June 30, 2017 \| $ / shares	$ 12.29

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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- Definition

Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(4)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

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- Definition

Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- References

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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No definition available.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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- Definition

Number of share options (or share units) exercised during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-Subparagraph (c)(1)(iv)(2)
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Summary of Stock Options Activity and Related Information (Detail)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Options
Beginning balance \| shares	20,000
Granted \| shares	0
Canceled \| shares	0
Exercised \| shares	0
Expired/Forfeited \| shares	0
Ending balance \| shares	20,000
Exercisable at June 30, 2017 \| shares	20,000
Weighted Average Exercise Price
Beginning balance \| $ / shares	$ 12.29
Granted \| $ / shares	0
Canceled \| $ / shares	0
Exercised \| $ / shares	0
Expired/Forfeited \| $ / shares	0
Ending balance \| $ / shares	12.29
Exercisable at June 30, 2017 \| $ / shares	$ 12.29