Stock-based Compensation - Stock-based Compensation Expense Recognized (Detail) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | $ 274,140 | $ 251,176 | $ 386,280 | $ 256,721 |
| Research and Development [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | 82,953 | 127,730 | 103,870 | 137,767 |
| Selling, General and Administrative [Member] | ||||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Total Stock based compensation | $ 191,187 | $ 123,446 | $ 282,410 | $ 118,954 |