Income Taxes - Primary Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Net operating losses	$ 66,405	$ 62,800
Stock-based compensation	1,648	873
Interest expense	1,494	0
Accrued liabilities and reserves	744	218
Fixed assets	51	72
Lease liability	658	0
Other temporary differences	23	315
Prepaid expenses	(186)	(176)
Right-of-use asset	(710)	0
Valuation allowance	(70,127)	(64,102)
Net deferred tax asset	$ 0	$ 0