SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accrued Expenses (Details) - USD ($) |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Accounting Policies [Abstract] | ||
| Accrued compensation and benefits | $ 621,905 | $ 697,334 |
| Other accrued expenses | 352,186 | 128,993 |
| Total | $ 974,091 | $ 826,327 |