Stock and Stock-based Compensation - Summary of Stock Option Activity (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Summary of stock option activity
Weighted Average Exercise Price, Beginning balance		$ 4.09
Weighted Average Exercise Price, Options exercised		4.09
Weighted Average Exercise Price, Options forfeited		4.09
Weighted Average Exercise Price, Options expired		$ 4.09
Summary of stock option activity
Outstanding, Beginning Balance	0	16,944
Stock options issued	0	0
Options exercised		(11,980)
Options expired		(4,964)
Outstanding, Ending Balance	0	0

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

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=6415400&loc=d3e5070-113901

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Number of options outstanding, including both vested and non-vested options.

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

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

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

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