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Stock-Based Awards (Details) - shares		9 Months Ended
	Jan. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Sep. 30, 2015
Stock-based awards
Options outstanding		7,122,455		5,167,164
Stock Option Valuation
Risk-free interest rate (as a percent)		3.53%	2.07%
Expected term (in years)		6 years 2 months 12 days	6 years 2 months 12 days
Expected volatility (as a percent)		77.73%	77.95%
Expected dividend yield (as a percent)		0.00%	0.00%
2017 Inducement Plan
Stock-based awards
Options outstanding		370,600
2015 Equity Incentive Plan
Stock-based awards
Number of shares authorized					1,643,872
Number of shares available for grant		2,890,919
Percentage increase to shares available for grant from common outstanding as of preceding December 31 (as a percent)		4.00%
Additional shares available	2,667,545
Options outstanding		6,295,647
2015 Equity Incentive Plan | Restricted stock unit awards
Stock-based awards
Number of shares outstanding		1,707,190
2012 Equity Compensation Plan
Stock-based awards
Number of shares available for grant		0
Options outstanding		456,208

X

- Definition

The percentage of increase to the number of shares available for grant from the common stock outstanding as of the end of the preceding calendar year.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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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Number of additional shares authorized for issuance under share-based payment arrangement.

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Number of options outstanding, including both vested and non-vested options.

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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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