Stockholders' Equity (Details 2) - $ / shares	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Non-employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of underlying stock at grant date		$ 3.37
Dividend yields
Expected volatility
Risk-free interest rates
Expected lives (in years)		10 years
Weighted-average grant date fair value		$ 3.36
Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of underlying stock at grant date	$ 0.53	$ 2.34
Dividend yields
Weighted-average grant date fair value	$ 0.52	$ 1.73
Minimum [Member] \| Non-employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility		73.00%
Risk-free interest rates		2.46%
Minimum [Member] \| Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	87.00%	68.00%
Risk-free interest rates	2.31%	2.01%
Expected lives (in years)	5 years	3 years
Maximum [Member] \| Non-employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility		76.00%
Risk-free interest rates		2.81%
Maximum [Member] \| Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	88.00%	75.00%
Risk-free interest rates	2.53%	2.58%
Expected lives (in years)	5 years 4 months 2 days	5 years 6 months

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The grant-date intrinsic value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ 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 (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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