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Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Income Tax Disclosure [Line Items]          
Deferred tax assets, valuation allowance $ 53,635   $ 53,635   $ 47,809
Effective tax rate     0.00% 0.00%  
Change in valuation allowance     $ 5,826    
Term of ownership change     an ownership change will occur if there is a cumulative change in ownership by 5% shareholders that exceeds 50 percentage points over a rolling three-year period    
ASU No. 2016-09 [Member]          
Income Tax Disclosure [Line Items]          
Excess tax benefits recognized in the provision for income taxes offset by valuation allowance $ 1,011 $ 707 $ 1,759 $ 2,751