Accrued Liabilities - Summary of Accrued Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued employee bonuses	$ 2,150,418	$ 3,049,109
Payroll and employee benefit accruals	698,969	369,275
Accrued professional fees	60,400	101,150
Accrued interest	156,492	45,544
Other accrued liabilities	292,186	181,708
Total accrued liabilities	$ 3,358,465	$ 3,746,786