XML 85 R65.htm IDEA: XBRL DOCUMENT v3.20.4
Stockholders' Equity - Narrative (Details) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Aug. 28, 2020
Jun. 30, 2020
May 12, 2020
May 31, 2018
Mar. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Jan. 01, 2020
May 13, 2016
Class of Stock [Line Items]                    
Convertible preferred stock, shares issued upon conversion, conversion price (in USD per share)           $ 27.20        
Share-based compensation           $ 15,647,523 $ 10,901,320 $ 10,654,622    
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized           $ 4,400,000 $ 3,400,000      
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition           1 year 4 months 24 days 1 year 8 months 12 days      
Number of options outstanding to purchase common stock (in shares)           8,906,624 9,265,390      
Aggregate intrinsic value of options outstanding           $ 24,200,000        
Aggregate intrinsic value for options exercisable           $ 16,800,000        
Options exercisable, remaining contractual term           5 years 8 months 12 days        
Number of options expected to vest (in shares)           8,906,624        
Options, expirations in period, weighted average exercise price (in USD per share)           $ 4.44 $ 6.27 $ 5.17    
Options, expirations in period (in shares)           78,750 324,502 119,091    
Options, grants in period, weighted average grant date fair value (in USD per share)           $ 6.87 $ 2.19 $ 2.86    
Proceeds from stock options exercised           $ 12,300,000 $ 113,000 $ 1,500,000    
Options, exercises in period, aggregate intrinsic value           14,200,000 25,000 910,000    
Employee                    
Class of Stock [Line Items]                    
Share-based compensation           14,500,000 9,800,000 10,200,000    
Research and Development Expense                    
Class of Stock [Line Items]                    
Share-based compensation           8,000,000.0 5,900,000 5,900,000    
General and Administrative Expense                    
Class of Stock [Line Items]                    
Share-based compensation           6,500,000 3,900,000 4,300,000    
Non Employee                    
Class of Stock [Line Items]                    
Allocated share-based compensation expense           $ 1,200,000 970,000 $ 302,000    
Number of options outstanding to purchase common stock (in shares)           845,375        
Restricted Stock Units (RSUs)                    
Class of Stock [Line Items]                    
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized           $ 10,900,000 $ 4,300,000      
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition           1 year 10 months 24 days 1 year 7 months 6 days      
Aggregate intrinsic value of unvested           $ 22,600,000        
Aggregate intrinsic value of vested           $ 13,500,000        
RSU's expected to vest (in shares)           2,558,052        
Weighted average grant date fair value (in USD per share)           $ 9.12 $ 3.09 $ 4.31    
Granted (in shares)           1,586,280        
2016 Incentive Plan                    
Class of Stock [Line Items]                    
Reserved number of shares under the Incentive Plan (in shares)           18,000,000       18,000,000
Number of potential shares authorized for issuance under a share-based compensation plan (in shares)                   2,000,000
Increase in number of shares authorized (in shares)                 2,000,000  
Number of shares available for grants under the Incentive Plan (in shares)           6,739,577        
Number of shares of vested restricted stock outstanding under the plan (in shares)           2,558,052        
Number of common stock shares outstanding under the Incentive Plan (in shares)           5,742,109        
Vesting period of incentive plan           3 years        
Contractual year term of incentive plan           10 years        
Award vesting period (in years)           3 years        
2016 Incentive Plan | Restricted Stock Units (RSUs)                    
Class of Stock [Line Items]                    
Weighted average grant date fair value (in USD per share) $ 12.06                  
Granted (in shares) 663,353                  
Grant date fair value $ 8,000,000.0                  
2016 Incentive Plan | Restricted Stock Units (RSUs) | Tranche One                    
Class of Stock [Line Items]                    
Vesting percentage 50.00%                  
2016 Incentive Plan | Restricted Stock Units (RSUs) | Tranche Two                    
Class of Stock [Line Items]                    
Vesting period of incentive plan 1 year                  
Vesting percentage 50.00%                  
Award vesting period (in years) 1 year                  
2007 Incentive Plan                    
Class of Stock [Line Items]                    
Number of common stock shares outstanding under the Incentive Plan (in shares)           3,164,515        
Vesting period of incentive plan           3 years        
Contractual year term of incentive plan           10 years        
Award vesting period (in years)           3 years        
Series C Preferred Stock                    
Class of Stock [Line Items]                    
Conversion of stock, shares converted (in shares)   14                
Convertible preferred stock, shares issued upon conversion (in shares)           3,309        
Common stock                    
Class of Stock [Line Items]                    
Conversion of stock, shares issued (in shares)   5,147                
Common stock | Sales Agreement                    
Class of Stock [Line Items]                    
Authorized amount       $ 100,000,000.0 $ 250,000,000.0          
Common stock | Prior Sales Agreement                    
Class of Stock [Line Items]                    
Remaining authorized amount         $ 0 $ 0        
Stock sale agreement, aggregate number of shares issued (in shares)         43,148,952          
Sale of stock, price per share (in USD per share)         $ 4.92          
Stock sale agreement, aggregate proceeds from issuance of stock         $ 208,200,000          
Common stock | New Sales Agreement                    
Class of Stock [Line Items]                    
Authorized amount     $ 250,000,000.0              
Remaining authorized amount           $ 0        
Agent fee       3.00%            
Stock sale agreement, aggregate number of shares issued (in shares)           22,915,934        
Sale of stock, price per share (in USD per share)           $ 10.91        
Stock sale agreement, aggregate proceeds from issuance of stock           $ 246,200,000