Quarterly report pursuant to Section 13 or 15(d)

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

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Stockholders' Equity - Schedule of Common Stock Reserved for Future Issuance (Detail) - shares
Mar. 31, 2018
Feb. 28, 2018
Class Of Stock [Line Items]    
Total reserved shares of common stock 13,736,753  
2014 Equity Incentive Plan    
Class Of Stock [Line Items]    
Total reserved shares of common stock 11,191,315  
2018 Inducement Plan    
Class Of Stock [Line Items]    
Total reserved shares of common stock 1,250,000 1,250,000
2014 Employee Stock Purchase Plan    
Class Of Stock [Line Items]    
Total reserved shares of common stock 1,020,438  
Options Granted Outside the Equity Plans    
Class Of Stock [Line Items]    
Total reserved shares of common stock 275,000