Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Restricted Stock Units - Additional Information (Detail)

v3.19.3
Stock Based Compensation - Restricted Stock Units - Additional Information (Detail) - Restricted Stock Units (RSUs) [Member]
9 Months Ended
Sep. 30, 2019
USD ($)
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Employee service share-based compensation, nonvested awards, compensation not yet recognized, share-based awards other than options | $ $ 14,201,155
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition 1 year 9 months 18 days
Non-Employee Equity Compensation Plan 2014 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period 288,176
Non-Employee Equity Compensation Plan 2014 [Member] | Minimum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, award vesting period 1 year
Non-Employee Equity Compensation Plan 2014 [Member] | Maximum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, award vesting period 3 years
2013 Equity Incentive Plan [Member] | Employee [Member] | Common Stock [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period 311,750
2013 Equity Incentive Plan [Member] | Minimum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, award vesting period 1 year
2013 Equity Incentive Plan [Member] | Maximum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, award vesting period 4 years
2017 Equity Inducement Plan [Member] | Employee [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period 40,500
Share-based compensation arrangement by share-based payment award, award vesting period 4 years