Stock-based Compensation - Valuation Assumptions (Details) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Dividend yield | 0.00% | 0.00% | 0.00% | 0.00% |
| Volatility | 106.00% | 87.00% | 104.00% | 82.00% |
| Minimum | ||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Risk-free interest rate | 2.75% | 1.83% | 2.70% | 1.83% |
| Expected term (in years) | 5 years | 5 years | 5 years | 5 years |
| Maximum | ||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Risk-free interest rate | 2.99% | 1.94% | 2.99% | 2.29% |
| Expected term (in years) | 6 years | 6 years | 10 years | 9 years |
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- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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. No definition available.
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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