Quarterly report pursuant to Section 13 or 15(d)

Stockholder's Equity - Additional Information (Detail)

v3.10.0.1
Stockholder's Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended
Mar. 08, 2018
Sep. 30, 2016
Jun. 21, 2016
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Sep. 14, 2018
Dec. 31, 2017
Schedule Of Capitalization Equity [Line Items]                  
Common stock, par value (in dollars per share)       $ 0.001   $ 0.001     $ 0.001
Common stock, shares authorized (in shares)       125,000,000   125,000,000     125,000,000
Common stock, shares issued (in shares)       47,193,062   47,193,062     28,971,651
Common stock, shares outstanding (in shares)       47,193,062   47,193,062     28,971,651
Common stock issued, net of expenses (in shares) 17,751,500                
Warrant liabilities fair value adjustment       $ (6,931) $ 1,638 $ (7,611) $ (2,809)    
Warrant liabilities       $ 5,200   $ 5,200      
Warrants to purchase common stock associated with Loan Agreement                  
Schedule Of Capitalization Equity [Line Items]                  
Exercise price of warrants (in dollars per share)   $ 3.6754              
Warrant expiration period   5 years              
Number of warrants issued to purchase common stock (in shares)   122,435              
Series 1 Warrant                  
Schedule Of Capitalization Equity [Line Items]                  
Number of warrants issued to purchase common stock (in shares)       115,550   115,550      
Proceeds from Warrant Exercises       $ 200          
Series 2 Warrant                  
Schedule Of Capitalization Equity [Line Items]                  
Exercise price of warrants (in dollars per share) $ 2.00                
Warrant term 5 years                
June 2016 Public Offering                  
Schedule Of Capitalization Equity [Line Items]                  
Exercise price of warrants (in dollars per share)     $ 3.00         $ 3.00  
Number of shares received per warrant (in shares)     0.45            
Warrant expiration period     5 years            
Number of warrants issued to purchase common stock (in shares)               4,218,750  
March 2018 Public Offering                  
Schedule Of Capitalization Equity [Line Items]                  
Common stock issued, net of expenses (in shares) 17,751,500                
Number of warrants issued to purchase common stock (in shares) 21,301,800                
March 2018 Public Offering | Warrant liability | Maximum                  
Schedule Of Capitalization Equity [Line Items]                  
Number of warrants issued to purchase common stock (in shares) 21,301,800                
March 2018 Public Offering | Series 1 Warrant                  
Schedule Of Capitalization Equity [Line Items]                  
Exercise price of warrants (in dollars per share) $ 1.85             $ 1.85  
Number of shares received per warrant (in shares) 0.75                
Number of warrants issued to purchase common stock (in shares)               13,198,075  
Warrant term 371 days                
March 2018 Public Offering | Series 1 Warrant | Maximum                  
Schedule Of Capitalization Equity [Line Items]                  
Number of warrants issued to purchase common stock (in shares) 13,313,625                
March 2018 Public Offering | Series 2 Warrant                  
Schedule Of Capitalization Equity [Line Items]                  
Exercise price of warrants (in dollars per share)               $ 2.00  
Number of shares received per warrant (in shares) 0.45                
Number of warrants issued to purchase common stock (in shares)               7,988,175  
March 2018 Public Offering | Series 2 Warrant | Maximum                  
Schedule Of Capitalization Equity [Line Items]                  
Number of warrants issued to purchase common stock (in shares) 7,988,175