Equity - Stock Option Activity (Detail) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Number of Options
Number of Options, Beginning Balance	5,426,165
Number of Options, Granted	2,052,500
Number of Options, Expired or Cancelled	(1,565,000)
Number of Options, Ending Balance	5,913,665	5,426,165
Number of Options, Exercisable	5,451,163
Weighted Average Exercise Price
Weighted Average Exercise Price, Beginning Balance	$ 1.99
Weighted Average Exercise Price, Granted	0.58
Weighted Average Exercise Price, Expired or Cancelled	2.60
Weighted Average Exercise Price, Ending Balance	1.34	$ 1.99
Weighted Average Exercise Price, Exercisable	$ 1.41
Weighted Average Remaining Contractual Life, Outstanding	5 years 6 months 4 days	4 years 10 months 21 days
Weighted Average Remaining Contractual Life, Exercisable	5 years 2 months 16 days
Aggregate Intrinsic Value, Outstanding	$ 42,603
Aggregate Intrinsic Value, Exercisable	$ 26,108

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.

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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
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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.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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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 grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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