Quarterly report pursuant to Section 13 or 15(d)

Note Payable - Additional Information (Detail)

v3.19.2
Note Payable - Additional Information (Detail) - Novartis [Member] - USD ($)
1 Months Ended 6 Months Ended
Dec. 05, 2018
Feb. 15, 2017
Dec. 31, 2016
Jun. 30, 2019
Dec. 19, 2016
Investment Agreement [Member]          
Debt Instrument [Line Items]          
Debt instrument, interest rate     6.00%    
Debt instrument, maturity date     Dec. 31, 2019    
Deferred revenue         $ 2,500,000
Convertible Promissory Note [Member]          
Debt Instrument [Line Items]          
Promissory note, principal amount   $ 15,000,000      
Debt instrument, interest rate   6.00%      
Debt instrument, maturity date   Dec. 31, 2019      
Promissory note conversion, description       The terms of the Novartis Note allowed the Company to convert the principal and accrued interest into the Company’s common stock at a conversion price equal to 120% of the 20-day trailing average closing price per share of the common stock immediately prior to the conversion date.  
Principal and accrued interest of note to be converted into common stock at conversion price, in percentage   120.00%      
Trailing period for average closing price per share of common stock   20 days      
Proceeds from issuance of convertible note payable   $ 15,000,000      
Convertible note payable   12,500,000      
Reduction of outstanding receivable   2,500,000      
Conversion of convertible note payable $ 15,000,000        
Conversion of convertible note payable to common stock 2,882,519        
Conversion price $ 5.77        
Fair value of convertible note payable       $ 12,500,000  
Convertible Promissory Note [Member] | Investment Agreement [Member]          
Debt Instrument [Line Items]          
Promissory note, principal amount   $ 15,000,000      
Principal and accrued interest of note to be converted into common stock at conversion price, in percentage   120.00%      
Conversion of convertible note payable $ 15,000,000        
Conversion of convertible note payable to common stock 2,882,519        
Conversion price $ 5.77