Stock-based Compensation - Stock-based Compensation Expense Recognized (Detail) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2015 |
Sep. 30, 2014 |
Sep. 30, 2015 |
Sep. 30, 2014 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | $ 272,749 | $ 34,109 | $ 659,029 | $ 290,830 |
| Research and Development [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | 76,579 | 18,217 | 180,449 | 155,984 |
| Selling, General and Administrative [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | $ 196,170 | $ 15,892 | $ 478,580 | $ 134,846 |