Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.20.1
Income Taxes - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Operating Loss Carryforwards [Line Items]      
Research credit carryforwards expiration year 2027    
Deferred tax asset, change in valuation allowance amount $ (700,000) $ 4,400,000 $ (9,000,000)
Cumulative change in ownership percentage 50.00%    
Period for cumulative change in ownership percentage 3 years    
Minimum percentage of likelihood for uncertain tax position to be recognized 50.00%    
Recognized interest or penalties on income tax $ 0 $ 0 $ 0
Federal and State [Member]      
Operating Loss Carryforwards [Line Items]      
Operating loss carryforwards 145,500,000    
Research credit carryforwards $ 8,300,000    
Operating loss carryforwards expiration year 2028    
State [Member]      
Operating Loss Carryforwards [Line Items]      
Operating loss carryforwards $ 76,400,000    
Research credit carryforwards $ 2,400,000