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Significant Accounting Policies - Summary of Potentially Dilutive Securities (Details) - shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]      
Potentially dilutive securities not included in the calculation of diluted net loss per share 1,029,467 513,869 2,457,897
Preferred Redeemable And Convertible Stock, Including Accumulated Dividends      
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]      
Potentially dilutive securities not included in the calculation of diluted net loss per share     2,406,894
Employee Stock Options      
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]      
Potentially dilutive securities not included in the calculation of diluted net loss per share 978,464 513,869  
Warrants outstanding      
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]      
Potentially dilutive securities not included in the calculation of diluted net loss per share 51,003   51,003