Annual report pursuant to Section 13 and 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.1
Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Revenues $ 42,736,000 $ 38,419,000 $ 51,741,000
Restricted cash 15,000 15,000 15,000
Allowance for doubtful accounts receivable 0 0  
Impairment of long-lived assets to be disposed of 0 0  
Deemed dividends $ 0 $ 0 0
Research and Development      
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Impairment of long-lived assets to be disposed of     $ 2,700,000
Minimum      
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Property and equipment useful lives 3 years    
Maximum      
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Property and equipment useful lives 5 years    
Balances without the Adoption of Topic 606      
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Revenues $ 43,500,000    
Accounting Standards Update 2014-09      
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]      
Cumulative effect of new accounting principle in period of adoption 10,327,000    
Revenues $ 43,484,000