v3.19.1
Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Operating Loss Carryforwards [Line Items]    
Federal corporate income tax rate 21.00% 34.00%
Tax Cuts and Jobs Act, change in tax rate, income tax expense (benefit)   $ 0
Net operating loss, limitation percentage 80.00%  
Income tax expense $ 0 0
Foreign taxes $ 0  
Operating loss carry forwards expiration period 2027  
Research and development tax credit carry forwards $ 3,772,000 $ 2,501,000
Tax credit carry forward expiration date 2029  
Maximum [Member]    
Operating Loss Carryforwards [Line Items]    
Federal corporate income tax rate   35.00%
Federal [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards $ 21,600,000  
Research and development tax credit carry forwards 2,700,000  
Federal [Member] | Expirable [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 9,000,000  
Federal [Member] | Nonexpirable [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 12,600,000  
State [Member]    
Operating Loss Carryforwards [Line Items]    
Net operating loss carry forwards 18,200,000  
Research and development tax credit carry forwards $ 1,400,000