Accrued Liabilities - Summary of Accrued Liabilities (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued employee bonuses	$ 289,107	$ 2,150,418
Payroll and employee benefit accruals	547,106	698,969
Accrued professional fees	97,644	60,400
Accrued interest	179,528	156,492
Other accrued liabilities	216,301	292,186
Total accrued liabilities	$ 1,329,686	$ 3,358,465