Stock-Based Compensation - Schedule of Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding	24,728,422
Number of Shares, Exercised	(71,084)
Number of Shares, Canceled/Forfeited	(135,000)
Number of Shares, Outstanding	24,522,338	24,728,422
Number of Shares, Exercisable	9,277,057
Weighted Average Exercise Price, Outstanding	$ 0.15
Weighted Average Exercise Price, Exercised	0.10
Weighted Average Exercise Price, Canceled/Forfeited	1.31
Weighted Average Exercise Price, Outstanding	0.15	$ 0.15
Weighted Average Exercise Price, Exercisable	$ 0.10
Weighted Average Remaining Contractual Life, Outstanding	2 years 4 months 24 days	2 years 7 months 6 days
Weighted Average Remaining Contractual Life, Exercisable	2 years 8 months 12 days

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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.

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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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Weighted average price of options that were either forfeited or expired.

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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.

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

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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 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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Number of share options (or share units) exercised during the current period.

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