Quarterly report pursuant to Section 13 or 15(d)

Description of Business and Basis of Preparation - Additional Information (Detail)

v3.19.1
Description of Business and Basis of Preparation - Additional Information (Detail)
Sep. 14, 2018
USD ($)
$ / shares
shares
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]  
Shelf registration maximum equity offering price | $ $ 175,000,000
Number of warrants issued to purchase common stock (in shares) 13,198,075
Aggregate amount receivable upon exercise of warrants | $ $ 28,600,000
Warrants, expiration date Mar. 14, 2019
Sales Agreement | Common Stock  
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]  
Shelf registration maximum equity offering price | $ $ 25,000,000
June 2016 Public Offering  
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]  
Number of warrants issued to purchase common stock (in shares) 4,218,750
Exercise price of warrants (in dollars per share) | $ / shares $ 3.00
March 2018 Public Offering | Series 1 Warrant  
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]  
Number of warrants issued to purchase common stock (in shares) 13,198,075
Exercise price of warrants (in dollars per share) | $ / shares $ 1.85
March 2018 Public Offering | Series 2 Warrant  
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]  
Number of warrants issued to purchase common stock (in shares) 7,988,175
Exercise price of warrants (in dollars per share) | $ / shares $ 2.00