Stock Based Compensation - Summary of Stock Options Granted Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding, January 1, 2020	3,131,266
Number of Options, Granted	861,257
Number of Options, Cancelled	(183,960)
Number of Options, Outstanding, March 31, 2020	3,808,563	3,131,266
Number of Options, Exercisable, March 31, 2020	1,819,443
Weighted Average Exercise Price, Outstanding, January 1, 2020	$ 8.53
Weighted Average Exercise Price, Granted	1.50
Weighted Average Exercise Price, Cancelled	8.86
Weighted Average Exercise Price, Outstanding, March 31, 2020	8.91	$ 8.53
Weighted Average Exercise Price, Exercisable, March 31, 2020	$ 12.08
Weighted Average Remaining Contractual Term (Years), Outstanding, January 1, 2020	8 years 8 months 12 days	8 years 10 months 24 days
Weighted Average Remaining Contractual Term (Years), Exercisable, March 31, 2020	8 years 3 months 18 days

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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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- Definition

For presentations that combine terminations, 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 or that expired.

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-Topic 718
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Weighted average price of options that were either forfeited or expired.

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- Definition

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

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

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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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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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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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