Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation -Summary of Stock-based Compensation Costs Recognized (Detail)

v3.19.3
Stock Based Compensation -Summary of Stock-based Compensation Costs Recognized (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Total $ 2,099,675 $ 3,852,656 $ 8,069,000 $ 12,804,744
Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Allocated share-based compensation expense 2,037,620 3,578,276 7,796,371 11,714,962
Performance Share Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Allocated share-based compensation expense 0 207,206 0 614,862
Employee Stock Purchase Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]        
Allocated share-based compensation expense $ 62,055 $ 67,174 $ 272,629 $ 474,920