Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation Plans (Additional Information) (Detail)

v3.19.1
Stock-Based Compensation Plans (Additional Information) (Detail) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]      
Exercisable Options Outstanding Shares 999,891    
Weighted average exercise price per share, Exercisable $ 4.73    
Unvested Options Outstanding, Shares 535,130    
Unvested Options Outstanding, Weighted average exercise price $ 5.80    
Unvested Options Outstanding Weighted average remaining life (yrs) 8 years 8 months 12 days    
Weighted average remaining contractual term on vested options 6 years    
Unrecognized stock compensation expense $ 2,700,000    
Weighted average recognition period 2 years 8 months 12 days    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term 6 years 10 months 24 days   7 years 2 months 12 days
Share-based Compensation $ 489,754 $ 508,451