Annual report pursuant to Section 13 and 15(d)

Collaboration and License Agreements - Additional Information (Detail)

v3.20.1
Collaboration and License Agreements - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 12 Months Ended
Dec. 05, 2018
Feb. 15, 2017
Dec. 31, 2016
Jun. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2020
Jul. 05, 2017
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                  
Collaboration and license agreement termination period         Sep. 30, 2019        
Conversion of convertible note payable         $ 0 $ 13,729,000 $ 0    
Cumulative catch-up adjustment in revenue       $ 4,600,000          
Novartis [Member] | 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] | Novartis [Member]                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                  
Non-refundable payment received     $ 50,000,000            
Proceeds from option exercised                 $ 7,000,000
Collaboration and license agreement termination period         Sep. 30, 2019        
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%            
Collaboration Agreement [Member] | Novartis [Member] | Scenario Forecast [Member]                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                  
Future milestone payments               $ 150,000,000  
Investment Agreement [Member] | Novartis [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            
Investment Agreement [Member] | Novartis [Member] | Convertible Promissory Note [Member]                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                  
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              
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