Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional information (Details)

v3.21.1
Income Taxes - Additional information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Income Tax Disclosure [Line Items]    
Operating Loss Carry forwards Not Subject To Expiration $ 41,800,000  
Operating Loss Carryforwards, Limitations on Use Percentage 80.00%  
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount $ 500,000 $ 700,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 21.00%
Unrecognized Tax Benefits $ 0  
California Franchise Tax Board [Member]    
Income Tax Disclosure [Line Items]    
Operating Loss Carry Forwards Expiration Year 2040  
Operating Loss Carryforwards $ 109,700,000  
Domestic Tax Authority [Member]    
Income Tax Disclosure [Line Items]    
Operating Loss Carry Forwards Expiration Year 2037  
Operating Loss Carryforwards $ 227,000,000  
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]    
Income Tax Disclosure [Line Items]    
Operating Loss Carry Forwards Expiration Year 2040  
Operating Loss Carryforwards $ 8,000,000  
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]    
Income Tax Disclosure [Line Items]    
Tax Credit Carryforward, Amount $ 9,200,000