Balance Sheet Components - Accrued Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accrued compensation and related:
Accrued vacation	$ 272,822	$ 287,326
Accrued payroll and commission	111,087	298,960
Accrued payroll tax	52,228	57,306
Accrued interest	356,778	917,482
Accrued consulting	257,492	368,862
Accrued contract manufacturing costs	386,591	106,607
Accrued legal costs	291,508	731,190
Accrued audit and tax services	188,967	96,150
Accrued other	1,004,782	2,075,558
Total	$ 2,922,255	$ 4,939,441