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Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Operating Loss Carryforwards [Line Items]    
Income tax expense $ 0 $ 0
Foreign taxes 0  
Research and development tax credit carry forwards 6,470,000 5,040,000
Interest Expense [Member]    
Operating Loss Carryforwards [Line Items]    
Reserve for uncertain tax positions 0 $ 0
State [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 60,700,000  
Research and development tax credit carry forwards 2,400,000  
Federal [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 72,900,000  
Research and development tax credit carry forwards 4,500,000  
Federal [Member] | Expirable [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 9,000,000.0  
Federal [Member] | Nonexpirable [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards $ 63,900,000  
Annual taxable income, percentage 80.00%  
Minimum [Member]    
Operating Loss Carryforwards [Line Items]    
Open tax year 2017  
Minimum [Member] | State [Member]    
Operating Loss Carryforwards [Line Items]    
Operating loss carry forwards expiration period 2027  
Tax credit carry forward expiration date 2029  
Minimum [Member] | Federal [Member]    
Operating Loss Carryforwards [Line Items]    
Operating loss carry forwards expiration period 2029  
Tax credit carry forward expiration date 2030