Summary of Significant Accounting Policies - Schedule of Assets Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) |
Sep. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Assets: | ||
| Cash and cash equivalents | $ 68,807,267 | $ 20,264,109 |
| Total assets | 68,807,267 | 20,264,109 |
| Level 1 [Member] | ||
| Assets: | ||
| Cash and cash equivalents | 68,807,267 | 20,264,109 |
| Total assets | $ 68,807,267 | $ 20,264,109 |