Annual report pursuant to Section 13 and 15(d)

Merger with Private Molecular - Additional Information (Detail)

v3.8.0.1
Merger with Private Molecular - Additional Information (Detail)
 1 Months Ended 5 Months Ended 12 Months Ended
Aug. 01, 2017
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2017
USD ($)
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
Jun. 01, 2017
USD ($)
Mar. 24, 2017
USD ($)
Business Acquisition [Line Items]              
Reverse stock split of common stock, description       11-for-1 reverse stock split      
Reverse stock split of common stock conversion ratio 11            
Exercise price per share on stock options after reverse stock split | $ / shares       $ 8.30 $ 1.85    
Stock compensation       $ 1,792,000 $ 109,000    
Operating expenses       21,242,000 12,499,000    
Loss on conversion of notes       4,619,000 0    
2014 Equity Incentive Plan              
Business Acquisition [Line Items]              
Stock compensation       $ 1,200,000      
Share Based Awards              
Business Acquisition [Line Items]              
Options to purchase shares of common stock | shares       963,681      
Threshold              
Business Acquisition [Line Items]              
Reverse stock split of common stock, description 11-for-1 reverse stock split            
Reverse stock split of common stock conversion ratio 11            
Exchange ratio of company common stock shares exchanged for each share owned by private molecular stockholders | shares 7.7844            
Threshold equity holders ownership interest 34.40%            
Private Molecular equity holders ownership interest 65.60%            
Threshold outstanding options assumed on merger date | shares 963,681            
Exercise price per share on stock options after reverse stock split | $ / shares $ 33.62            
Stock compensation $ 0            
Settlement of threshold bridge loan $ 4,010,000 $ 4,000,000          
Fair value inputs discount rate 12.00%            
Transaction costs associated with Merger $ 2,000,000            
Principal amount           $ 2,000,000 $ 2,000,000
Promissory note interest rate             1.00%
Operating expenses     $ 320,000        
Threshold | Eliminations              
Business Acquisition [Line Items]              
Transaction costs associated with Merger     $ 5,400,000 $ 5,400,000 0    
Loss on conversion of notes       4,600,000 0    
Stock-based compensation expense       1,200,000 0    
Severance costs       2,900,000 0    
Interest expense       300,000 200,000    
Interest expense       $ 100,000 $ 100,000    
Threshold | In-process Research and Development (IPR&D)              
Business Acquisition [Line Items]              
Adjustment to previously recorded IPR&D due to correction of merger purchase price   $ 677,000