Stock Based Compensation - Stock Compensation Expense, Restricted Stock Units (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	$ 6	$ 74
RSUs | Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	0	10
RSUs | Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	0	12
RSUs | General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	6	52
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	0	3
Restricted Stock | General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	0	3
Series D Preferred Stock | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	158	33
Series D Preferred Stock | Restricted Stock | Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	47	17
Series D Preferred Stock | Restricted Stock | Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock compensation expense	$ 111	$ 16