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Income Per Common Share - Additional Information (Detail) - shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Earnings Per Share [Abstract]      
Dilutive effect of outstanding restricted stock awards after application of the Treasury Stock Method 122,000 117,000 61,000
Common stock shares excluded from calculation of diluted net income per common share 30,000