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Employee Benefit Plans - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]      
Minimum percentage of employee contribution to defined contribution plan 1.00%    
Amount of employee contribution to defined contribution plan $ 19,500 $ 19,000  
Employer matching contributions to defined contribution plan 0 0  
Employee Age Fifty and Above [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Amount of employee contribution to defined contribution plan 26,000 25,000  
Supplemental Employee Retirement Plan [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Benefit obligations in excess of the fair value of plan assets $ 10,805,326 9,723,866 $ 9,038,825
Defined benefit plan, assumption used to calculate discount rate description The discount rate is based on matching the projected cash flows of the plan to the Citigroup Pension Discount Curve.    
Contributions to the plan $ 544,261 367,989  
Other Noncurrent Liabilities [Member] | Supplemental Employee Retirement Plan [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Benefit obligations in excess of the fair value of plan assets   $ 10,800,000 $ 9,700,000