Balance Sheet Components - Accrued Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accrued compensation and related:
Accrued vacation	$ 287,326	$ 264,304
Accrued payroll	300,040	150
Accrued payroll tax	57,306	30,617
Accrued interest	917,482	659,961
Accrued consulting	660,370	1,785
Accrued research and development costs	106,607	668,850
Accrued legal costs	439,682
Accrued audit and tax services	96,150	40,000
Deferred rent		4,584
Accrued other	2,074,478	533,882
Total	$ 4,939,441	$ 2,204,133