Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.10.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
1 Months Ended 3 Months Ended 9 Months Ended
Aug. 31, 2013
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2018
USD ($)
bank
Sep. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Subsidiary, Sale of Stock [Line Items]                
Cash, cash equivalents, and restricted cash   $ 16,408,000 $ 8,749,000 $ 16,408,000 $ 8,749,000 $ 11,469,000 $ 35,656,000  
Upfront payment received $ 1,500,000              
Deferred revenue estimated performance period 70 months              
Revenue recognized from upfront payments   64,000 $ 64,000 193,000 $ 193,000      
Other receivable due from R-Pharm   175,000   175,000   $ 251,000    
Secured Debt | Term Loan                
Subsidiary, Sale of Stock [Line Items]                
Term loan, face amount               $ 15,000,000
License and Service [Member]                
Subsidiary, Sale of Stock [Line Items]                
Revenue recognized from upfront payments   100,000   200,000        
Sales Agreement                
Subsidiary, Sale of Stock [Line Items]                
Deferred offering costs   $ 200,000   $ 200,000        
Banking Concentration Risk [Member]                
Subsidiary, Sale of Stock [Line Items]                
Number of banks | bank       1