v3.19.2
Stock-Based Compensation - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended
May 31, 2019
Mar. 31, 2019
Mar. 31, 2017
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Options to purchase common stock, granted           4,622,428    
Unrecognized compensation cost related to stock options       $ 5,956,838   $ 5,956,838    
Weighted-average fair value of options granted       $ 0.62   $ 1.11    
Stock Option [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Vesting period           48 months    
Compensation expense       $ 604,661 $ 822,850 $ 1,226,346 $ 1,554,223  
Weighted average period expected to be recognized           2 years 7 months 6 days    
Restricted Stock [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Compensation expense       $ 0 $ 54,907 $ 0 $ 403,255  
2017 Stock Option and Incentive Plan [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Common stock shares available for issuance   1,623,520 4,600,000          
Percentage applied to the outstanding shares as annual increase in number of shares authorized for issuance   4.00% 4.00%          
2017 Stock Option and Incentive Plan [Member] | Stock Option [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Common stock shares available for issuance       969,529   969,529   2,959,562
Term of options to be granted           10 years    
Shares issued for special retention grant 2,419,050              
Options to purchase common stock, granted       2,801,600 1,515,200 4,622,428 1,515,200  
2017 Stock Option and Incentive Plan [Member] | Stock Option [Member] | One-year Anniversary [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Vesting percentage           25.00%    
2017 Stock Option and Incentive Plan [Member] | Stock Option [Member] | First Installment [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Vesting percentage 50.00%              
Option, vesting date Jun. 30, 2020              
2017 Stock Option and Incentive Plan [Member] | Stock Option [Member] | Second Installment [Member]                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Vesting percentage 50.00%              
Option, vesting date Jun. 30, 2021