Stock-Based Compensation - Status of options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Number of options
Options outstanding	1,380,312	825,205
Options vested and expected to vest	1,380,312
Options vested and exercisable	699,519
Weighted average exercise price
Options outstanding (in dollars per share)	$ 10.06	$ 12.15
Options vested and expected to vest (in dollars per share)	10.06
Options vested and exercisable (in dollars per share)	$ 10.48
Weighted average contractual term and aggregate intrinsic value
Options outstanding (in years)	7 years 10 months 21 days
Options vested and expected to vest (in years)	7 years 10 months 21 days
Options vested and exercisable (in years)	6 years 8 months 19 days
Options outstanding (in dollars)	$ 258
Options vested and expected to vest (in dollars)	258
Options vested and exercisable (in dollars)	$ 258

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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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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Number of fully vested and expected to vest exercisable options that may 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 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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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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