Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

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Income Taxes - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Income Taxes Disclosure [Line Items]      
Income tax provision $ 0 $ 0  
Increase in valuation allowance 12,800,000    
Unrecognized benefits 0 0 $ 1,143,000
Accrued interest or penalties 0 $ 0  
State      
Income Taxes Disclosure [Line Items]      
Research and development credits $ 800,000    
Year research and development credits begin to expire 2033    
Federal      
Income Taxes Disclosure [Line Items]      
Net operating loss carryforwards $ 125,500,000    
Year net operating loss carryforwards begin to expire 2024    
Tax loss carryforwards expiration year     2037
Research and development credits $ 3,500,000    
Year research and development credits begin to expire 2022