Quarterly report pursuant to Section 13 or 15(d)

Capital Structure - Summary of Common Stock Reserved for Future Issuance (Detail)

v3.19.1
Capital Structure - Summary of Common Stock Reserved for Future Issuance (Detail) - shares
Mar. 31, 2019
Dec. 31, 2018
Class of Stock [Line Items]    
Common Stock reserved for future issuance 40,071,858 38,430,911
Stock Options [Member]    
Class of Stock [Line Items]    
Common Stock reserved for future issuance 9,084,744 7,187,885
Warrants [Member]    
Class of Stock [Line Items]    
Common Stock reserved for future issuance 30,987,114 31,243,026