Significant Accounting Policies - Schedule Of Outstanding Potentially Dilutive Securities Excluded In Calculation Of Diluted Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Significant Accounting Policies [Line Items]
Outstanding potentially dilutive securities excluded in calculation of diluted net loss per share	15,224,224	10,485,467
Redeemable Convertible Preferred Stock
Significant Accounting Policies [Line Items]
Outstanding potentially dilutive securities excluded in calculation of diluted net loss per share	13,200,115	9,131,999
Common Stock Options
Significant Accounting Policies [Line Items]
Outstanding potentially dilutive securities excluded in calculation of diluted net loss per share	1,315,625	1,084,243
Warrants to Purchase Redeemable Convertible Preferred Stock
Significant Accounting Policies [Line Items]
Outstanding potentially dilutive securities excluded in calculation of diluted net loss per share	708,484	269,225