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Earnings and Dividends per Share (Additional Information) (Details) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Earnings and Dividends Per Share [Abstract]        
Number of options excluded from computation of diluted earnings per share 426,918 1,298,659 476,162 1,234,126