Stock-Based Compensation - Summary of Outstanding Stock Options and Related Activity (Detail) - $ / shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding Shares, beginning balance	139,000	373,000
Granted Shares	30,000	0
Canceled / expired Shares	(9,000)	(234,000)
Outstanding Shares, ending balance	160,000	139,000
Exercisable Shares	123,000	116,000	307,000
Vested and expected to vest Shares	136,000
Outstanding Weighted Ave. Exercise Price, beginning balance	$ 5.69	$ 22.51
Canceled / expired, Weighted Ave. Exercise Price		32.54
Outstanding Weighted Ave. Exercise Price, ending balance	4.88	5.69
Exercisable, Weighted Ave. Exercise Price	5.64	$ 6.16	$ 26.48
Vested and expected to vest, Weighted Ave. Exercise Price	$ 4.13

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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=109197908&loc=d3e5070-113901

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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.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

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

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No definition available.

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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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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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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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