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Earnings Per Share - Additional Information (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Stock Compensation Plans [Member]        
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]        
Options to purchase common stock, Shares 12,000 600,000 12,000 600,000