Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Number of Shares, Options Outstanding, Beginning	673,885	254,171
Number of Shares, Options Granted	698,750	456,718
Number of Shares, Options Exercised/ Expired/ Forfeited	(28,500)	(37,004)
Number of Shares, Options Outstanding at Ending	1,344,135	673,885
Number of Shares, Options Exercisable	531,528	290,818
Weighted Average Exercise Price, Outstanding, Beginning	$ 19.82	$ 47.43
Weighted Average Exercise Price, Options Granted	0.62	3.16
Weighted Average Exercise Price, Options Exercised/ Expired/ Forfeited	0.98	3.90
Weighted Average Exercise Price, Outstanding at Ending	10.24	19.82
Weighted Average Exercise Price, Options Exercisable	$ 28.66	$ 50.19
Aggregate Intrinsic Value, Outstanding, Beginning
Aggregate Intrinsic Value, Options Granted
Aggregate Intrinsic Value, Options Exercised/ Expired/ Forfeited
Aggregate Intrinsic Value, Outstanding at Ending
Aggregate Intrinsic Value, Options Exercisable
Weighted- Average Remaining Contractual Life (in Years), Outstanding, Beginning	8 years 2 months 12 days	7 years 3 months 19 days
Weighted- Average Remaining Contractual Life (in Years), Options Granted	9 years	8 years 7 months 6 days
Weighted- Average Remaining Contractual Life (in Years), Outstanding at Ending	8 years 4 months 24 days	8 years 2 months 12 days
Weighted- Average Remaining Contractual Life (in Years), Options Exercisable	7 years 4 months 24 days	6 years 10 months 25 days

Weighted- Average Remaining Contractual Life (in years), Options granted.

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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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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
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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 combined weighted average of the accumulated differences between the fair values on underlying shares and exercises prices to acquire such shares as of the grant date on options that were either forfeited or lapsed.

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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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The grant-date intrinsic value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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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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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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