Stock-Based Compensation - Summary of Stock Option Activity (Parenthetical) (Details) - Options Issued and Outstanding - shares	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted	871,010
Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted	7,200	46,860

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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