Quarterly report pursuant to Section 13 or 15(d)

Collaboration and License Agreements - Additional Information (Detail)

v3.19.1
Collaboration and License Agreements - Additional Information (Detail) - Novartis [Member] - USD ($)
1 Months Ended
Dec. 05, 2018
Feb. 15, 2017
Dec. 31, 2016
Jul. 05, 2017
Convertible Promissory Note [Member]        
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]        
Debt instrument, interest rate   6.00%    
Debt instrument, maturity date   Dec. 31, 2019    
Debt instrument, conversion price percentage   120.00%    
Promissory note, principal amount   $ 15,000,000    
Conversion of convertible note payable $ 15,000,000      
Conversion of convertible note payable to common stock 2,882,519      
Conversion price $ 5.77      
Collaboration Agreement [Member]        
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]        
Non-refundable payment received     $ 50,000,000  
Proceeds from option exercised       $ 7,000,000
Maximum milestone payments to be received upon achievement of certain milestones     $ 650,000,000  
Percentage of observational study costs     50.00%  
Assumed percentage of observational study costs upon completion of ongoing Phase 2b trails     100.00%  
Required prior written notice period for termination of collaboration agreement     180 days  
Percentage of reduction in milestone and royalty payments     50.00%  
Investment Agreement [Member]        
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]        
Debt instrument, maximum borrowing capacity     $ 15,000,000  
Debt instrument, interest rate     6.00%  
Debt instrument, maturity date     Dec. 31, 2019  
Debt instrument, conversion price percentage     120.00%  
Number of days trailing average closing price of common stock immediately prior to the conversion date     20 days  
Investment Agreement [Member] | Convertible Promissory Note [Member]        
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]        
Promissory note, principal amount   $ 15,000,000    
Conversion of convertible note payable $ 15,000,000      
Conversion of convertible note payable to common stock 2,882,519      
Conversion price $ 5.77