Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Number of Options, Shares, Beginning Balance	1,862,569
Options Outstanding, Number of Options, Granted, Shares	0	195,975
Options Outstanding, Number of Options, Exercised, Shares	(2,870)	(487)
Options Outstanding, Number of Options, Cancelled, Shares	(276,420)	(165,622)
Options Outstanding, Number of Options, Shares, Ending Balance	1,583,279		1,862,569
Options Outstanding, Number of Options Exercisable, Shares, as of September 30, 2020	1,062,960
Options Outstanding, Number of Options, Vested and expected to vest, Shares as of September 30, 2020	1,583,279
Options Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 9.09
Options Outstanding, Weighted Average Exercise Price, Exercised	4.14
Options Outstanding, Weighted Average Exercise Price, Cancelled	9.28
Options Outstanding, Weighted Average Exercise Price, Ending Balance	9.07		$ 9.09
Options Outstanding, Weighted Average Exercise Price, Exercisable as of September 30, 2020	8.90
Options Outstanding, Weighted Average Exercise Price, Vested and expected to vest as of September 30, 2020	$ 9.07
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	7 years 11 months 12 days		8 years 7 months 20 days
Options Outstanding, Weighted Average Remaining Contractual Life (Years), Exercisable as of September 30, 2020	7 years 10 months 2 days
Options Outstanding, Weighted Average Remaining Contractual Life (Years), Vested and expected to vest as of September 30, 2020	7 years 11 months 12 days
Options Outstanding, Aggregate Intrinsic Value, Beginning Balance	$ 99
Options Outstanding, Aggregate Intrinsic Value, Ending Balance	588		$ 99
Options Outstanding, Aggregate Intrinsic Value, Exercisable as of September 30, 2020	508
Options Outstanding, Aggregate Intrinsic Value, Vested and expected to vest as of September 30, 2020	$ 588

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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

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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 fully vested and expected to vest options outstanding that can be converted into shares under option plan. 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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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for 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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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. 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 share options (or share units) exercised during the current period.

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