Stock-based Compensation - Stock-based Compensation Expense Recognized (Detail) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock-based compensation | $ 164,588 | $ 106,306 | $ 310,417 | $ 224,630 |
| Research and Development [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock-based compensation | 35,784 | 9,192 | 72,087 | 18,048 |
| General and Administrative [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock-based compensation | $ 128,804 | $ 97,114 | $ 238,330 | $ 206,582 |