STOCK BASED COMPENSATION - Assumptions (Details)	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Expected term (years)		6 years 21 days
Expected volatility		70.78%
Risk-free interest rate		2.59%
Expected dividend yield	0.00%	0.00%
Maximum
Expected term (years)	6 years 2 months 8 days
Expected volatility	70.75%
Risk-free interest rate	1.83%
Minimum
Expected term (years)	5 years 2 months 4 days
Expected volatility	69.99%
Risk-free interest rate	0.37%

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

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Name Accounting Standards Codification
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