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Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Income Tax Disclosure [Line Items]    
Income tax benefits $ 0 $ 0
Net operating loss carryforwards, federal 174,028,000  
Net operating loss carryforwards, state 192,346,000  
Increase in valuation allowance 14,276,000 23,307,000
Unrecognized tax benefits $ 0 $ 0
Description of income tax examinations There are currently no pending tax examinations.  
Tax Cuts and Jobs Act of 2017, description of corporate tax payers Corporate taxpayers may carryback NOLs originating during 2018 through 2020 for up to five years, which was not previously allowed under the 2017 Tax Act. The CARES Act also eliminates the 80% of taxable income limitations by allowing corporate entities to fully utilize NOL carryforwards to offset taxable income in 2018, 2019 or 2020. Taxpayers may generally deduct interest up to the sum of 50% of adjusted taxable income plus business interest income (30% limit under the 2017 Tax Act) for tax years beginning January 1, 2019 and 2020. The CARES Act allows taxpayers with alternative minimum tax credits to claim a refund in 2020 for the entire amount of the credits instead of recovering the credits through refunds over a period of years, as originally enacted by the 2017 Tax Act.  
CARES Act, percentage of eliminates of taxable income 80.00%  
Tax Cuts and Jobs Act of 2017, maximum percentage of interest deducted by tax payers 50.00%  
CARES Act, percentage of interest deducted by tax payers 30.00%  
CARES Act, percentage of corporate charitable deduction limit 25.00%  
CARES Act, period of qualified improvement property for cost-recovery 15 years  
CARES Act, percentage of bonus depreciation 100.00%  
Maximum [Member]    
Income Tax Disclosure [Line Items]    
Net operating loss carryback period 5 years  
Federal [Member]    
Income Tax Disclosure [Line Items]    
Income tax benefits $ 0  
Net operating loss carryforwards, subject to expiration 43,127,000  
Net operating loss carryforwards, not subject to expiration $ 130,901,000  
Net operating loss carryforwards, beginning to expiring year 2035  
Research and development tax credit carryforwards $ 8,139,000  
Research and development tax credit carryforwards, expiration year 2035  
State [Member]    
Income Tax Disclosure [Line Items]    
Income tax benefits $ 0  
Net operating loss carryforwards, beginning to expiring year 2035  
Research and development tax credit carryforwards $ 2,699,000  
Research and development tax credit carryforwards, expiration year 2030