Preferred Stock Warrants - Additional Information (Details) - $ / shares		2 Months Ended
	Oct. 22, 2018	Sep. 30, 2018	Aug. 31, 2018
Subsequent Event | Common Stock
Class Of Warrant Or Right [Line Items]
Warrants converted into shares	632,887
Subsequent Event | Initial Public Offering
Class Of Warrant Or Right [Line Items]
Warrants converted into shares	13,225,114
Subsequent Event | Initial Public Offering | Common Stock
Class Of Warrant Or Right [Line Items]
Warrants converted into shares	632,888
Subsequent Event | Weighted-average
Class Of Warrant Or Right [Line Items]
Exercise price of warrant	$ 0.12
Redeemable Convertible Preferred Stock | Subsequent Event
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase shares	632,887
2018 Series C-1 Warrants | Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase shares			368,582
Exercise price of warrant		$ 0.12	$ 0.12
Class of warrants exercised		144,948
2014 Series B, Convertible Debt Series C-1, and 2018 Series C-1 Warrants | Redeemable Convertible Preferred Stock | Subsequent Event | Initial Public Offering
Class Of Warrant Or Right [Line Items]
Warrants issued to purchase shares	632,887
2014 Series B, Convertible Debt Series C-1, and 2018 Series C-1 Warrants | Redeemable Convertible Preferred Stock | Subsequent Event | Weighted-average | Initial Public Offering
Class Of Warrant Or Right [Line Items]
Exercise price of warrant	$ 0.12