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Percentage of total common stock outstanding.

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Aggregate number of common shares reserved for future issuance.

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

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Gross number of share options (or share units) granted during the period.

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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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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of shares issued under share-based payment arrangement.

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Description of terms of award under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Number of non-vested options outstanding.

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Number of share options (or share units) exercised during the current period.

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Stock Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-based compensation
New shares available for future issuance (in shares)				534,320
Vesting period (in years)				4 years
Contractual life (in years)				10 years
Granted (in shares)	840,450			1,824,375
Unvested stock options (in shares)		2,395,657		2,395,657
Unrecognized compensation cost		$ 9,100		$ 9,100
Weighted average amortization period				2 years 6 months
Exercise of stock options (in shares)		0		1,449
Aggregate intrinsic value of options exercised			$ 500	$ 1	$ 500
Aggregate intrinsic value of options outstanding		$ 44		44
Aggregate intrinsic value of options exerciseable		$ 44		$ 44
Weighted average grant date fair value, options granted (in USD per share)		$ 1.12		$ 3.18
Share-based Payment Arrangement, Tranche One
Stock-based compensation
Percentage of shares to vest	50.00%
Share-based Payment Arrangement, Tranche Two
Stock-based compensation
Percentage of shares to vest	8.33%
2019 Plan
Stock-based compensation
Aggregate number of shares of our common stock initially reserved for issuance (in shares)		2,919,872		2,919,872
Vesting period (in years)				10 years
Percentage of common stock outstanding		4.00%		4.00%
ESPP
Stock-based compensation
Vesting period (in years)				10 years
Percentage of common stock outstanding		1.00%		1.00%
Aggregate number of shares issued				133,580