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Earnings Per Share - Number of Potentially Dilutive Common Shares (Detail) - shares
shares in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Earnings Per Share [Abstract]        
Potential common shares (in shares) 1,082 1,082 1,082 1,082