Convertible Preferred Stock and Stockholders' Deficit - Summary of Common Stock Issued and Reserved for Issuance (Parenthetical) (Details)	6 Months Ended
	Jun. 30, 2018
Series A-2 Convertible Preferred Stock
Stockholders Deficit [Line Items]
Convertible preferred stock converted to common stock, ratio	3.539%
Series B Convertible Preferred Stock
Stockholders Deficit [Line Items]
Convertible preferred stock converted to common stock, ratio	4.103%
Series C Convertible Preferred Stock
Stockholders Deficit [Line Items]
Convertible preferred stock converted to common stock, ratio	5.071%