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Earnings Per Share Reconciliation - Additional Information (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Earnings Per Share [Abstract]        
Antidilutive securities excluded from computation of earnings per common share 251,000 222,000 234,000 199,000