Stock Incentive Plans - Schedule of Assumptions (Details) - $ / shares	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Shares available for future stock incentive awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.39%	2.18%	1.61%	2.41%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term	5 years 6 months 21 days	5 years 10 months 13 days	6 years 10 days	6 years 10 days
Expected volatility	89.70%	88.71%	88.12%	87.56%
Weighted-average fair value of common stock (in dollars per share)	$ 2.92	$ 2.48	$ 2.36	$ 2.42
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.00%	2.07%	0.00%	2.10%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term	0 years	5 years 5 months 26 days	0 years	5 years 6 months
Expected volatility	0.00%	88.46%	0.00%	88.44%
Weighted-average fair value of common stock (in dollars per share)	$ 0	$ 2.04	$ 0	$ 2.04

Weighed-average fair value relating to the share-based payment award.

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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.

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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.

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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.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Name Accounting Standards Codification
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