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Employee Benefit Plans - Summary of Components of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income (Detail) - Supplemental Employee Retirement Plan [Member] - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Net periodic benefit cost    
Interest cost $ 279,778 $ 340,302
Net periodic benefit cost $ 279,778 $ 340,302