Annual report pursuant to Section 13 and 15(d)

Common Stock - Stock Options - Additional Information (Detail)

v3.20.4
Common Stock - Stock Options - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for options currently outstanding 227,442 50,498  
Weighted average fair value of stock options granted $ 8.76    
Unrecognized compensation expense related to stock options granted $ 2,200,000 $ 1,800,000  
Estimated grant date fair value of stock options vested 1,000,000 900,000 $ 1,000,000
Aggregate intrinsic value of options exercised 0 $ 0 $ 0
Aggregate intrinsic value of the outstanding options 0    
Aggregate intrinsic value of the exercisable outstanding options $ 0    
Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Weighted-average period, restricted stock awards 2 years 2 months 4 days 2 years 2 months 4 days  
Restricted Stock Unit [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
Common shares reserved for awards currently outstanding 231 500  
Weighted-average period, restricted stock awards 6 months 29 days    
2018 Equity Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 1,459    
Award expiration period 10 years    
2018 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2018 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2018 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2018 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2018 Equity Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 215,514    
Common shares reserved for options currently outstanding 214,055    
2017 Equity Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 10 years    
2017 Equity Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2017 Equity Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2017 Equity Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2017 Equity Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2017 Equity Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 13,156    
2010 Performance Incentive Plan [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award expiration period 10 years    
2010 Performance Incentive Plan [Member] | Minimum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2010 Performance Incentive Plan [Member] | Minimum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 1 year    
2010 Performance Incentive Plan [Member] | Maximum [Member] | Employees and Consultants [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 4 years    
2010 Performance Incentive Plan [Member] | Maximum [Member] | Board of Directors [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Award vesting period 3 years    
2010 Performance Incentive Plan [Member] | Stock Options [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for issuance under incentive plan 462    
Common shares reserved for options currently outstanding 231    
2010 Performance Incentive Plan [Member] | Restricted Stock Unit [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares reserved for awards currently outstanding 231