Stockholders' Equity - Options Other Info (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Options outstanding
Closing price of Company's stock (in dollars per share)	$ 0.57
Employee Stock Option
Options outstanding
Intrinsic value of options exercisable	$ 0
Unrecognized compensation expense	$ 2,400
Weighted average remaining period for recognition of unrecognized compensation expense	2 years 11 days
Per-share weighted-average grant date fair value of options granted (in dollars per share)	$ 0.62	$ 1.04
Employee Stock Option \| Weighted-average
Weighted-average assumptions:
Expected term of options (in years)	6 years 3 months 18 days	6 years 3 months 18 days
Risk-free interest rate (as a percent)	1.50%	2.50%
Expected volatility (as a percent)	95.40%	75.40%
Dividend yield (as a percent)	0.00%	0.00%

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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

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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.

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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

Price of a single share of a number of saleable stocks of a company.

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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.

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- Definition

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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