Quarterly report pursuant to Section 13 or 15(d)

Stockholders' (Deficit) Equity - Schedule of Common Stock Reserved for Future Issuance (Details)

v3.19.2
Stockholders' (Deficit) Equity - Schedule of Common Stock Reserved for Future Issuance (Details) - shares
Jun. 30, 2019
Dec. 31, 2018
Temporary Equity [Line Items]    
Reserved common stock 7,540,249 6,250,381
Common Stock    
Temporary Equity [Line Items]    
Reserved common stock 3,903,653 3,111,718
Common Stock Awards Issued And Outstanding    
Temporary Equity [Line Items]    
Reserved common stock 458,190 311,240
2004 and 2018 Equity Incentive Plan    
Temporary Equity [Line Items]    
Reserved common stock 2,717,022 2,525,610
2018 Employee Stock Purchase Plan    
Temporary Equity [Line Items]    
Reserved common stock 389,571 230,000
Warrants to Purchase Common Stock    
Temporary Equity [Line Items]    
Reserved common stock 71,813 71,813