Stock-Based Compensation - Schedule of Black Scholes Option-Pricing Model (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
2015 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			6 months
Volatility	0.00%	0.00%	60.90%	0.00%
Risk-free interest rate	0.00%	0.00%	0.00%	0.00%
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 2 months 12 days	0 years	6 years 1 month 6 days	6 years 1 month 6 days
Volatility	77.60%	0.00%	79.00%	79.50%
Risk-free interest rate	1.00%	0.00%	0.80%	0.80%

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.

+ References

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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

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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