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Net Income per Common Share - Additional Information (Detail) - $ / shares
3 Months Ended 6 Months Ended
Jul. 31, 2021
Jul. 31, 2020
Jul. 31, 2021
Jul. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive common shares 160,000 560,000 180,000  
Anti-dilutive common shares exercise price, minimum $ 38.09 $ 18.81 $ 35.85  
Anti-dilutive common shares exercise price, maximum $ 46.42 $ 46.42 $ 46.42  
Performance Stock Units (PSUs)        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive common shares     30,001 706,794